Fix Driver Irql Not Less Or Equal Error

May 28th, 2009

Device drivers are required to allow operating systems to communicate with computer hardware. In Windows XP and Vista quite a few device drivers are included with the installation. But for a lot of hardware, special device drivers are required. If drivers are corrupted or not installed properly, Windows will report a device error. One of the device errors that the Windows can report is a “Driver Irql Not Less Or Equal” error. This can result in a blue screen.

The irql less or not equal error basically indicates a problem with the system resources used by a hardware device, such as I/O address ranges, DMA, and IRQ’s. The IRQ is an interrupt request, which is used by the hardware to claim CPU time from the system. The number of IRQ’s in a PC however, is limited so sometimes different devices end up sharing an IRQ.

The Driver Irql Not Less Or Equal error can happen in Windows XP as well as in Windows Vista. The irql error can happen with the NDIS.SYS file, if the error is caused by a network or modem card, but other hardware can also be the cause of the conflict. Because of the severity of the this kernel level problem, the error results in a blue screen or stop error. Driver errors would normally be obvious because the blue screen error lists a .SYS file.

Using the .SYS filename, you can find out which device or hardware is responsible for the error. You can then disable the hardware in the Windows Device Manager to see if the device is really the cause of the error.

Running a memory test is also a good idea, as faulty memory can be the cause for many stop errors. In the Bios, disable the quick start, so the full diagnostics is run, and a memory test can be run using software.

In most cases the ‘irql not less or equal’ error can be solved by updating the drivers for the device causing the error. Also make sure you update your Windows and antivirus software, as some of these errors are not caused by hardware, but software problems. You can use the Windows device manager to uninstall any currently installed driver for the device and the reinstall the latest driver. When you reboot your PC after uninstalling the drivers, Windows will detect the new hardware, which allows you to install the latest drivers for the device.

If you do not have the drivers for the device in error, or are not comfortable in using the Windows device manager, you can also use a driver update program to find, download and update all device drivers for you. Driver update software will accurately identify your hardware, including the device in error, and automatically install the latest drivers for it. This can solve driver irql not less or equal errors.

If updating the drivers does not fix the issue, try loading the default BIOS options. This will ensure that RAM timing, FSB timing, and CPU timing are not causing the error. Further you can check the resource assignments on the devices in the Windows Device Manager to check if there is an irq conflict.

Check for resource conflics for devices

Microsoft further advices that you try to load the last known good configuration using the start menu (press F8 during boot). But you do need to make sure that the problem does not introduce itself again as a result of changes or updates. So the best way is to find the real cause of a blue screen error and fix it.

In case you are still running Windows 2000, there is another possible cause for the driver_irql_not_less_or_equal error, which is related to dismounting drive volumes. Check the Microsoft knowledge base article on this to fix it.

Entry Filed under: Device Errors

92 Comments Add your own

  • 1. Blue Screen on Vista 64-b&hellip  |  July 18th, 2009 at 5:29 am

    [...] are the problem. Not the psu. Thats stupid to even think a driver crash would be the psu……or-equal-error __________________ System: E7400: O/C 3.8 GHz ~ xfx 780i sli mobo: O/C 1600 FSB ~BFG GTX 285 OC~ [...]

  • 2. NicholasHall  |  July 28th, 2009 at 7:57 am

    good info thanx

  • 3. Blue Screen Windows XP  |  November 25th, 2009 at 6:30 am

    My operating system is windows XP, and i get this error screen usually when I run a large process(like having 3 or more tabs in the web browser). It says the error is caused by a system file called portcls.sys I could not find this in device manager but i did find it in ‘My Computer’. I do not know whether to remove this file in fear of causing damage to my computer that is irreversable. If you could respond to this comment for me please it would help a great deal.- Thank You

  • 4. Andy  |  December 10th, 2009 at 1:59 pm

    The portcls.sys file is related to the sound driver on your system. In most cases you can fix it by updating the sound driver or installing the right one.
    Disabling your sound is also something you can try to check if it is really the sound driver.

  • 5. Switchblade-DK  |  March 5th, 2010 at 6:46 pm

    I have similar problem, but it says, that it is the CPhilMAS64.sys file that is the matter.

    What is the CPhilMAS64.sys file, and how can I update it?

  • 6. Jay  |  March 5th, 2010 at 9:27 pm

    But how can I update a driver when it stops in the middle of installing XP. Message includes atapi.sys
    I am at a loss.

  • 7. Andy  |  March 26th, 2010 at 4:04 am

    @Switchblade-DK – I am not familiar with that file, and the only thing I could find on it is that it might be related to a VideoMate TV tuner. Do you have a TV Tuner, and if so, do you know the brand and model?
    Your Windows version is also helpful

    @Jay – The atapi.sys is a disk or CD-rom related driver, so your Windows setup CD might have a problem (try copying it if possible), or you have a problem with your hard disk. Do a full NTFS disk format if you can before installing XP.

  • 8. matt  |  April 13th, 2010 at 2:06 pm

    when i turn my computer on it makes it as far as the windows xp loading screen than it blue screens on me and comes up with DRIVER_IRQL_NOT_LESS_OR_EQUAL at the top than at the bottom it has USBPORT.SYS ADDRESS F771A323 BASE AT F770FOOO, DATE STAMP41107D62. I cant get into windows to troubleshoot, i already flashed the bios and it didnt work. i have a asus A7N8X-LA motherboard, i dont want to buy a new motherboard and processer if i dont have to. can anybody help me out?

  • 9. Andy  |  April 13th, 2010 at 7:19 pm

    @matt – From your details it appears there is a problem with the USB driver. The bios would not actually help here I think.
    Have you tried booting in Safe Mode (F8 during computer startup)? If that works, you can try “sfc /scannow” at the command prompt to check and correct the Windows system files.
    If you can’t boot at all, you will need a Recovery CD or Windows install CD to boot in the recovery console.

  • 10. boshack  |  May 17th, 2010 at 4:16 pm

    hello everyone, I got this problem on my COM recently.
    I’ve reinstalled my windows, so I thougth it would have resolve this blue screen error but now I’m still seeing it.
    from my conclusion I’ve found my expectation of the cause of this problem whenever I use my COM and the softwares.
    which is:
    Orbit Downloader 2.8.17
    Utorrent 2.0.2
    Mozilla Firefox ver 3.5.1
    Windows extreme se7en 2010 Xgamer

    do you think some of those programs I’ve used can cause the error?

    I’m waiting the error to happen again so I can give those “command thing” to you guys (I’m sorry I’m so noob in this thing)
    thank you

  • 11. Andy  |  May 17th, 2010 at 6:14 pm

    @boshack – The first 2 programs should not have anything to do with the irql error. The Xgamer software is a bootable Windows image for gaming, right?
    So that could cause it if the right drivers are not installed.
    You should be able to tell by not using that for a while and see if the error happens at all.

  • 12. James Dima  |  May 30th, 2010 at 6:05 am

    thanks for the info. great job also to those who are giving free tech support.

  • 13. Monitor wont detect Compu&hellip  |  June 7th, 2010 at 4:48 am

    [...] try your fix when i get back home good find! heres a fix to your problem…or-equal-error [...]

  • 14. pornchai supawan  |  July 21st, 2010 at 9:50 am

    Thank for knowledge.

  • 15. Dan  |  July 26th, 2010 at 11:15 am

    If a safe mode boot cannot be achieved, then it is not a driver issue. It is either an incompatible memory module or a bad memory module. At this point, you won’t be able to test the ram through windows.

    Download Ubuntu or a recovery disk that can enable you to boot into a command line shell (aka DOS-mode) and run memtest86+. If it crashes, the memory modules are incompatible. If the ram modules are damaged, errors will occur.

    If you are able to boot into a safe mode of Windows, go to System Properties > Hardware > Device Manager and check to see if there are conflicts. Uninstall the drivers that are causing the problem or disable the hardware, if possible and if that item is not needed. If that does not solve the problem, then you’ve got some investigative work to do (a combination of removing hardware and starting up the computer while checking each piece or replacing parts).

  • 16. thebesttib  |  August 9th, 2010 at 11:24 pm

    my computer is not getting on…so how will install new driver?

  • 17. Verne James  |  November 21st, 2010 at 7:06 pm

    I too have the blue screen problem and have tried a lot of the suggestions. it says “NDIS.SYS Address b9dc6150 base at b9dad000 Date stamp 481073e0. I have windows XP, i purchased and used a driver update program. in problem devices i get the keyboard, network card and ps2 mouse. I replaced the key board and it is off the list, disabled and uninstall driver to network card and it dissapears for 1 start up. replace the mouse with USB optical. Still get conflict with the mouse and card for network. I use a USB network connection. the blue screen only happens after i let it go to sleep mode. happening almost everytime now. I appreciate any help.

  • 18. Andy  |  November 21st, 2010 at 8:52 pm

    @Verne James – Try checking the Power Management tab in the network device properties (Device Manager). Changing the power management settings for the USB network device might help.
    If not, check the power management of the USB Root Hub devices under the Universal Serial Bus Controller group. Disable the option to allow the computer to turn off the device.

  • 19. Verne James  |  November 22nd, 2010 at 10:12 pm

    I’ll give that a try and let you know, you guys are so helpful,,, thanks again


  • 20. Verne James  |  November 23rd, 2010 at 12:53 am

    it still acts the same, I’ll just set it to not sleep and it works flawless. thanks

  • 21. AngrywitTDI.sys  |  December 31st, 2010 at 3:22 pm

    The file i am having trouble with TDI.sys, what is it and how can i fix it?

  • 22. A guy  |  January 13th, 2011 at 2:09 am

    running windows 7 x64, ram 8 go ok video 1 go ok (drivers too), bios ok, my computer already got bac k to the seller cause ia had multiple crashes first for irql then implying win32k.sys files, , cache_manager, pfn_list (_corrupted), etc, so normally it got fixed, but ive had 2 crashes since yesterday always driver_irql_not_less_or_equal.
    I think it’s while running mozilla cause im writing now with ie x64 and it lasts more than the five minutes under firefox. So is it possible that running mozilla makes my comp have a driver irql?

  • 23. Andy  |  January 13th, 2011 at 8:17 am

    @AngrywitTDI.sys – The TDI.sys error is related to the network driver from Microsoft. You can try restoring it from the original Windows CD using the EXPAND command.

    @ A guy – I have not heard that problem with FireFox before, but FireFox has crashed a lot more on my system as well since version 3.6. Never ends in a blue screen error though, just an application crash and restart.
    Application related irql_not_less_or_equal are still more often memory or driver related.
    You have tested you memory with something like memtest86?
    And try reinstalling your network drivers as well.


  • 24. A guy  |  January 13th, 2011 at 2:34 pm

    my comp is freshly repared , i had the ram reseted and memtest ran 4 times with no error, i have a ati radeon hd 5800 graphic and installed the latest update on the amd website, after running a driveragent it says that i lack 5 drivers, but downloading them is not free, and i cant find em, these are for the “ide drivers standard double channel pci”, the “smbus ati I/O”,and
    the realtek pci gtc family controls

  • 25. Aguy  |  January 13th, 2011 at 3:22 pm

    I ran memtest for 4 hours, no problem, reseted my ram too.
    So I have one more prob now, as the screen also tells me page_fault_in_nonpaged_area
    don’t understand,
    i’ve used the driver test on the site but couldnt pay, so i know that some drivers i got are outdated but i cant find the updates, like smbus communication ati I/O driver, realtek pcie gbe family controller
    got a ati radeon hd 5800 video, can be that? damn…

  • 26. Andy  |  January 13th, 2011 at 3:40 pm

    @A guy – The problems you are facing could very well be driver related. Most commonly video and network drivers cause these type of serious problems (although it can always be another driver). Try looking up the drivers at the manufacturer’s site if you can’t get the driver update programs.

  • 27. Satashi  |  January 23rd, 2011 at 3:29 am


    So I’ve been having this issue with my computer. I have Windows 7, in case you need to know.

    I have the same error with the whole, IRQL-NOT-LESS-OR-EQUAL issue; however, mine says the techincal Infomrtion is

    iaStor.sys is the issue.

    Not in direct words, but…it’s still really annoying.

  • 28. Robin  |  February 8th, 2011 at 7:37 pm

    I started getting this error on one of my computers (I have several) after I installed a new Netgear Router. The computer in question has an older Linksys B network card that should be able to access the household network. But every attempt to connect generates the IRQL error. It’s an older computer, running XP, so I don’t want to invest in a netgear access device for it–any suggestions?

  • 29. Andy  |  February 8th, 2011 at 10:52 pm

    @Satashi – The iastor.sys driver file is related to the Intel Matrix Storage Manager, so I would recommend you first try and update the Intel Chipset System drivers on your computer.

    @Robin – The brand of router and network card really do not need to be the same. Chances are that you would get the error while connecting to any router.
    Have you already tried reinstalling or updating the drivers for your Linksys network card?
    Other things to look at are the settings for the network card itself (in the Device Manager). Try disabling power management for the network device or check resource allocation options if possible (IRQ, I/O address, DMA).

  • 30. Teo  |  February 9th, 2011 at 6:17 pm

    Hi, mine win7..
    I have 2x 1GB RAM installed..

    Until i plugged in the USB wireless adapter.. blue screen occur.. AND, that make my computer only read 1 GB of RAM.. only sometime (just turned on the next day with the Wireless plugged off) it reads 2GB..

    What should i do? Why the USB wireless make my RAM unreadable?

  • 31. october  |  February 16th, 2011 at 2:11 pm

    i have windows XP on my computer but when i tried to format my disk with windows lastXp OS i get a blue screen message saying driver_IRQL_not_Less_or_Equal
    what shall i do to make my computer work agian?

  • 32. Andy  |  February 19th, 2011 at 6:28 pm

    @Teo – Have you tried updating or reinstalling he USB drivers for the wireless adapter already?
    Also look at the USB chipset drivers (typically Intel or AMD).

    @october – Did you try deleting all partitions, creating new ones and doing a full NTFS format before installing? If not, try that.

  • 33. Brian  |  February 20th, 2011 at 10:48 am

    My 1.5 year old Gateway just BSOD on me, I get the IRQL_not message with the iastor.sys error.

    I have reinstalled, repartitioned the OS from the facotry disks 3 times now… I get the same error everytime… Worked like a charm for year and half, and then 3 days ago. BOOM BSOD, Sometimes I can work for 5 minutes, other times I can’t even get through the login 3x in a row without the BSOD. any ideas??? I’ve trid driver updates, and now these are the original ones that works when I got it, nothing….

  • 34. Robin  |  February 20th, 2011 at 9:03 pm

    Well, I tried re-installing the driver from the Linksys disk (which Windows claimed was not logo-compliant), then tried uninstalling/reinstalling the network adapter. Neither worked. I am ready to uninstall/reinstall the entire OS and start from scratch…?

  • 35. Andy  |  February 20th, 2011 at 10:03 pm

    @Brian – Th iastor.sys is related to the Intel Management Engine, which can still be quite a few things, but did you try installing the latest Intel chipset drivers for your system already?
    I would also try checking the RAM, open the computer case if you can and remove and reinsert it. And a third thing to try is to load the default BIOS settings.

    @Robin – Reinstalling Windows is always an option, but if it is really an older network card, I suggest you check the resource assignment as well. In the network card properties window you can see the IRQ and I/O address assignments and also if there is any conflict with other devices.
    Possibly you need to manually allocate the IRQ in the BIOS (but this is really for older systems).

  • 36. SS  |  March 8th, 2011 at 7:38 pm

    Hi I had a RAM upgrade from 1 GB to 2 GB. Ever since my system restarts while browsing internet. I have run through scan and deleted all viruses. Reformatted C: and reinstalled XP OS. Still i get the error only when I browse internet. The frequency of restart increases if i browse video and audio files over net. System is quite ok when not browsing

  • 37. SS  |  March 8th, 2011 at 7:39 pm

    I am sorry, I forgot to name the error its “IRQL_Not_Les_Or_Equal” with blue screen

  • 38. Andy  |  March 10th, 2011 at 7:37 pm

    @SS – Memory is rather critical in a PC, so when you expand RAM, first of all make sure the new memory is the same as the existing module (access speed particularly).
    If in doubt, run a memory test using memtest86, to check the RAM.
    You can also try loading the default BIOS settings in the BIOS to reset the RAM timing to the default.

  • 39. Richard  |  May 1st, 2011 at 2:29 pm

    Andy: I’m getting a brief blue screen on a boot-up from “cold” on an IBM ThinkPad T23 with XP Pro SP3. So brief in fact that that it’s impossible to identify anything apart from “IRQL_Not_Less_Or_Equal”. I then get the black screen with safe mode and other options: selecting “Start Windows normally” seems to work okay, but obviously I don’t want to go through this every time and would like to check there’s not something seriously nasty developing!

    This has only happened since I installed more RAM: from your March 10th comment I get the impression that it’s not a good idea to have two chips of different sizes? The original was 256K, the new one is 512K. I also have a Seagate 500GB external hard drive connected, although this everything was fine with that when I just had the 256K chip.

    Once the system has booted it runs absolutely fine and if I turn it off and then restart I don’t get the blue screen: I haven’t tried a shutdown/restart though. Any thoughts/solutions gratefully received!

  • 40. Andy  |  May 3rd, 2011 at 3:41 pm

    @Richard – As long as you install the RAM according to the specifications of the manufacturer (or motherboard manual), it should work. But in practice, most problems with RAM occur if different memory modules are used (either size or speed). That is the reason I generally advise against that.
    So in your case it could simply be that the temperature of the RAM modules affect the timing.

    You can configure Windows not to automatically reboot on a system error, so you can read the full BSOD content and see if anything else relevant is mentioned (a .SYS file for example would indicate a driver error).

  • 41. Richard  |  May 3rd, 2011 at 3:56 pm

    Thanks for your response. From that I get the impression the solution is to remove the 256K RAM and/or replace it with another 512K?

  • 42. Andy  |  May 3rd, 2011 at 4:20 pm

    @Richard – Apart from my suggestions to exclude the driver cause, yes, that would be my suggestion to solve the BSOD.

  • 43. Attila  |  May 5th, 2011 at 11:32 am

    Hello. I have a difficult problem. It appear at a regular time 2 BSOD erors. On is with PFN list error and one is with Driver irql not equal or less error. I don’t know exactly what create me this problem. First i have 3GB Ram on my Toshiba A300 laptop and i was thinking to make an update. These 3gb are produced by Samsung ddr2 667mhz frequency. I remove the 1gb slot and i buy a new Kingston 2gb ddr2 667mhz slot.I don’t know in the beginig the bus for these Ram slots. When i tested it with MemTest84 i noticed that the Samsung have 400bus and the Kingston 333. Could be these a problem? I don’t find when i buy the memory these information somewhere. Can you help me? Thanks in advance

  • 44. Andy  |  May 5th, 2011 at 3:54 pm

    @Attila – The Toshiba user manual will have the details about the memory expansion.
    In general for a A300 laptop the RAM slots can take 512 MB, 1GB or 2GB memory modules of the type PC2-5300.
    But I would always try to match the brand, type and speed for the RAM modules, and not mix them, to prevent problems.
    You can try changing the RAM timing in the BIOS (start with loading the default settings), to see if you can resolve the problem, but using identical modules is the best option to make sure the RAM is not causing your errors.

  • 45. Jimmy  |  August 3rd, 2011 at 4:41 am

    I was having this IRQL_NOT_LESS_OR_EQUAL blue screen of death a couple times per day. I followed this articles advice and reviewed each piece of hardware thru Windows Device Manager. I only looked at the “Resource” tab, which indicates whether there are conflicts present. Some devices don’t end up having a “Resource” tab, which is fine. I found a conflict on my “ENECIR Receiver”, which is the infrared receiver. I simply uninstalled and then reinstalled it. The conflict disappeared and no more issues!! Much easier fix than I anticipated!

  • 46. Ertan  |  August 4th, 2011 at 6:30 pm

    Thank you ver much… i solved the problem with the eror mesasage at the blue screen ***.sys… thanx again…

  • 47. Janis  |  August 15th, 2011 at 11:00 pm

    Am new to this blue screen malarky but had it a few times now. Managed to jot down pssdk pf.sys before it crashed and restarted. I have googled this but no joy don’t know what it relates to any ideas?
    am running HP Pavilion Laptop windows 7. Many thanks…

  • 48. Andy  |  August 16th, 2011 at 12:03 am

    @Janis – Are you certain that is the filename? I am also not familiar with pssd pf.sys, but there is more on a file called pssdklbf.sys, which seems to be related to a program called tbbmeter.
    You an try disabling the auto reboot on system errors in Windows, so you can check the .SYS filename on the blue screen properly.

  • 49. Janis  |  August 16th, 2011 at 12:44 am

    Hi Andy many thanks for your reply. AHA. I installed tbbmeter to monitor wifi use. Yes that looks like it what is best, uninstall that program? really appreciate your help

  • 50. Andy  |  August 16th, 2011 at 2:32 pm

    @Janis – From what I read it seems to be something in a 3rd party library that tbbmeter is using. They adviced to turn off the TCP/UDP monitoring, which limits the captured information of course. Uninstalling is definitely an option to get rid of the BSOD errors.
    In general I would not keep monitoring software installed or running all the time anyway. It can give very useful information during testing or analysis, but you need to consider that there is always some overhead in the measuring…

  • 51. JAime Alvelo  |  August 17th, 2011 at 3:58 am

    Problem connecting to Internet via modem on HP Pavillion ze4420 US portable with Windows Xp (SP-3). working fine for a couple of years but last saturday I tried connecting via modem and connection to server was ok. But once i opened my browser it kicked me out of the operating system with the following message in blue screen
    DRIVER_IRQL_NOT_LESS_OR_EQUAL Windows XP blue screen
    STOP: 0X000000D1
    I did update of driver and now it go blue screen as soon as it connected to server via the modem. A friedn suggested I flash the Bios but I went to see the Bios flash programs at HP tecnical support and the descriptions of what they fixed had nothing to do with this problem. Advice? Could it be a faulty old modem?

  • 52. JAime Alvelo  |  August 17th, 2011 at 4:00 am

    Works fine with ethernet cable

  • 53. Andy  |  August 17th, 2011 at 8:12 pm

    @JAime Alvelo – Although faulty hardware can definitely cause blue screen errors like that, it is more common that it is a software or driver problem. Does not even need to be the modem driver itself. But that would be indicated by the filename (with the .SYS extension) on the blue screen itself. Does that show a .SYS filename when the 0x000000D1 error occurs?
    If not, you can also use the minidump to find out what file the most likely cause of the bsod is.

  • 54. Sunny  |  August 20th, 2011 at 5:43 pm

    Hi Andy,
    i get the blue screen mesage IRQL-Not less……. and says NDIS.SYS, PHYSICAL MEMORY DUMP COMPLETED….
    Please advise me what can be the possible error and how can i get rid of this problem.

    I am using Windowa XP on Acer travelmate 4000

  • 55. Andy  |  August 21st, 2011 at 3:44 pm

    @Sunny – The NDIS.SYS points at the network driver, so your problem is most likely related to the ethernet or wifi driver.
    If you recently updated the network driver, or installed some network related software, try reversing that (you can also try using a previous restore point).
    If it does not help, simply try reinstalling the network drivers for the ethernet card and the wifi device.
    I think the ethernet is broadcomm, and the wifi is Acer or Intel.

  • 56. Mario  |  August 26th, 2011 at 10:46 pm

    Wow, thanx 4 the help! Much appreciated!

  • 57. Ben  |  September 24th, 2011 at 11:24 pm

    My computer was running fine for many years then something happened. I lost half the Xp OS. It happened under Crucial Ballistix Memory. I could not see my files and could only see them if I took a different path. I called Microsoft about the problem and they told me they would call me back, I never heard from them again. I was running 2 gigs of ram, 2 sticks. I was able to get the OS up but now I am only able to run 1 stick of the memory. I checked both sticks of memory and they check good but I can only use one stick otherwise I get the blue screen of death. Both sticks of memory were a matching pair. The computer is now ten years old. I still use it and it is still fast with one stick but when I had two sticks it ran faster than any other computer I had or had seen, matching the speeds of today’s new computers. Everything seemed to point to bad memory but when I transferred the memory to a different machine the memory checks and runs well. I can either put the memory in one bank or the other but not both. Craziest problem that I ever did encounter. The machine is a Abit ISC-7 with a 478 P 4 Hyperthreading 3.2 processor pulled back to 2.8. It runs on the edge of HOT always, especially before the crash. When I render a video the heat alarm sounds after several minutes. I have to open the case and start my Chinese battery operated fan for additional cooling to the existing copper large pie size heatsink for the temp to come down enough to stop the alarm. But she is still a nice machine. It ran originally as if a engineer of motherboards had a crew of techs tuning my computer for best performance everyday, then they left after several years and now my machine lacks the racers edge. It’s very puzzling to me and I have read many blogs on this subject. I don’t think I will ever get the machine back to where it once was. My last attempt will be to reformat and lay down a fresh Xp, maybe, but technology moves forward and computers are very inexpensive currently. So much so that they can be had for ten dollars complete.

  • 58. Andy  |  September 26th, 2011 at 4:24 pm

    @Ben – Reading through your story, it seems very possible to me that the motherboard is the cause.

  • 59. cody  |  September 26th, 2011 at 9:34 pm

    so im having a similar issue however when i look up the stop code im given a completely different error message i tried to start my computer in every possible way and it either restarts itself or goes to the same bsod the stop code ive been given is 0x0000007f(0×0000000000000008,0×0000000080050033,0x00000000000006f8,0xfffffa6000bd2p17) but it also says driver_irql_not_less_or_equal

  • 60. cody  |  September 26th, 2011 at 9:37 pm

    also im running on windows vista so im not sure if i may have copied the error down correctly or not

  • 61. heatherwilkes  |  September 27th, 2011 at 9:50 am

    Dear Author,
    I like the way you explained this, in a combination of plain english and technical terms, b/c not everyone is a CIS major, but almost everyone gets a scary blue screen eventually. 4 stars, very well done & thanks! Wish me luck!

  • 62. Andy  |  September 28th, 2011 at 1:57 am

    @cody – If the stop error happens every time, even in Safe Mode, then it is most likely a hardware issue, since only the minimal required drivers are loaded in Safe Mode.
    Have you checked the temperature? Is the system running hot?
    Other than that, you can test the RAM to exclude the memory as the cause of the BSOD.

  • 63. JAime Alvelo  |  September 28th, 2011 at 3:41 am

    Regarding my Blue Screen of Death when I connected to the Internet via modem you were right it was not the modem. I have Conexant modem in my portabke and bought aan external USB modem. Uninstalled the Conexant and ran the USB modem….same problem–BSOD. So I ran MSCONFIG and de-activated all the start up programs. Then I connected to the Internet and here I am. Thus I conclude that it is what you were saying- a driver/program conflict for memory space or IRQ of modems software with other program software.
    The challenge is determining what or which specific program loaded at startup causes the crash? Not having a diagnostic software for this I would have to slowly add each of the programs I disabled at startup to see which causes the crash…Now with 35 programs at startup and not remembering when none of them were installed I have the challenge of finding the time to disable each one by one until I find the correct one (the bad guy)…there must a better way.

  • 64. JAime Alvelo  |  September 28th, 2011 at 5:02 am

    Andy: In the process of using the USB modem I had to remove the Conexant Modem Driver two times as I had not taken it out of my portable. That meant going to Start; Control Panel; Phone and Modem Options; Modems; Click on Conexant and Remove. Tha means that the system each time I did a Restart would find the device and install the driver. Well I went back to Run: MSCONFIG and enabled all the Statup files. I did a Windows System check for IRQ & Memory Conflicts and also ran Dr. Watson’s Diagnostic Tool. I found no conflicts. So I disconnected my USB modem and tried my old Conexant internal modem again. To my surprise the PC connected alright to my internet provider; I waited a minute or two; nothing happened; I loaded my Internet Explorer and it loaded nicely; waited a couple of minutes and I’m still connected. I call that luck. My intuition tells me that removing the modem driver and having it reinstalled by the device manager automatically when finding the hardware may have fixed a corrupted modem driver. That is my hypothesis but as I’m not sure…it’s pure luck that I was able to fix it.
    PD: Reading this section helped

  • 65. Andy  |  September 28th, 2011 at 2:39 pm

    @JAime Alvelo – Thanks for sharing your experiences. It is very possible for a hardware configuration to become corrupted. Normally the hardware would not function correctly, but in your case it even resulted in blue screen errors.
    Uninstalling the device and then letting Windows redetect and install it again will reset the configuration, but it does not always fix the issue. I am glad it did in your case though!

    PS. Regarding the disappearing of your solution, that’s because the blog has comment moderation on. Comments need to be approved before they remain permanent. Your comments will remain visible now.

  • 66. Jaime Alvelo  |  September 28th, 2011 at 4:58 pm

    Thanks Andy!

  • 67. Tóth Mátyás  |  October 11th, 2011 at 2:46 am

    I have a Logitech USB mouse.
    I only get the driver irql fault when it is pluged in, but I not always get the fault when it is pluged in. I used the mouse like a week and I did not get any faults. Yesterday I started to get dose bluescreens again.
    Could it be because of the mouse?

    P.S.: Most of the time I got the bluescreen when I did nothing with my computer, not moving the mouse or writing, just reading or not even using it.

  • 68. Andy  |  November 9th, 2011 at 1:14 pm

    @Tóth Mátyás – Although the mouse could be the cause, that would most likely be a USB error, I would also recomment running a memory (RAM) test. Random irql errors like that are more often caused by memory errors, since memory is used randomly and dynamically.
    But simply try unplugging the mouse, start your computer and let it run for a day to see if that is the cause.

  • 69. Matt  |  December 3rd, 2011 at 2:56 am

    I’ve XP and have been getting the irql error-

    I get the message when streaming video or when my kids play games on the internet.

    I’m in the process of updating out of date drivers, but have lost the irql error information and am loathe to intentionally get the BSOD on purpose again.

    Any guess which driver is causing the problem? Thanks for any help that can be provided, this is very informative stuff!

  • 70. Andy  |  December 3rd, 2011 at 8:26 am

    @Matt – The best way to see which driver is indeed the mention of a .SYS filename on the BSOD itself. But if you cannot or do not want to get the BSOD to see that, it is also possible to identify the most likely driver from the minidump file.
    But you need to run the minidump through the windows debugger to see that, and that takes a bit of effort and knowledge to install and run.
    So in your case, from your description, I would recommend that you update or reinstall the network driver (or wireless lan driver if you use wireless Internet), and also the video driver.

  • 71. jenny  |  January 3rd, 2012 at 2:18 pm

    hi… can anyone help me? i get the error driver irql nott less or equal very often now… first it was like 2-3 times a day… looked into device manager checked each one(resources) i found one that it is in system devices called pci standard pci-to-pci bridge that it says “this device isn’t using any resourcers because it has a problem” driver details: \system32\DRIVERS\pci.sys please can anyone tell what should i do? thanks a lot..

  • 72. Andy  |  January 3rd, 2012 at 3:54 pm

    @jenny – The PCI bus is a bus type on the motherboard, and can be used for expanding a computer’s functions (like a video card or network card).
    The PCI bus is supported by the motherboard chipset, and as such, it would be best to first try and reinstall the chipset drivers for your computer motherboard.
    That can be an Intel chipset driver, VIA, nForce, really depends on the computer brand or motherboard brand. If you can let us know the details of your computer, I can try and provide a link. Also include your Windows version please.

    Another option is to run a command prompt, and type “SFC /SCANNOW” followed by Enter.
    This will check the Windows system files and tell you if something is wrong (and offer to fix it). You need to use an administrator account for this.

  • 73. jenny  |  January 3rd, 2012 at 7:44 pm

    hi andy… thanks for your reply… i have a presario cq60 212ea and i run windows 7 on it… hope you can help me… tks…

  • 74. jenny  |  January 3rd, 2012 at 8:45 pm

    tried with comand prompt as you said no violations were found…

  • 75. Andy  |  January 3rd, 2012 at 11:03 pm

    @jenny – The compaq presario cq60 uses an nforce chipset from nvidia, so from the HP website you can download the nforce chipset drivers for that model.
    The link I provided is for the 32-bit version. If you have Windows 7 64-bit, you need to select that.

  • 76. Joanne  |  January 17th, 2012 at 12:15 am

    I am getting the blue screen and errors…when i see the blue screen it shows agnfilt.sys as the file name… anyone know what this is… ?

  • 77. Joanne  |  January 17th, 2012 at 12:25 am

    Driver IRQL not less or equal error…. addl info…from my earlier post… My husband is getting the same error with the same file. (agnfilt.sys) We work for the same company…both have the same standard image and the same file showing up on the BSOD …the

  • 78. Andy  |  January 17th, 2012 at 2:12 pm

    @Joanne – The agnfilt.sys is part of the AT&T AGN client. Have you recently installed that software, or made changes to it?
    You can try upgrading to the latest version of the AGN client first.
    But I would also run a check for viruses and malware, as some rootkit viruses can also cause this behavior.

  • 79. Ricardo Pollack  |  March 27th, 2012 at 2:51 pm

    Hello, I have an Asus that came with Vista, and I loaded windows 7 premium 32 into it. I repeatedly get the blue screen Driver IRQL event when I talk on Skype or occasionally another soft phone — that is the only thing that prompts the BSOD — anybody have an idea?

  • 80. Ellie  |  March 28th, 2012 at 11:47 am

    I would like to try the methods suggested here to solve the issue but when I try log into Safe Mode or Startup Repair, the computer will say it is loading files and then loop back up to the start-up screen. Sometimes it will turn to a blank screen; once it told me something similar to: “The file could not be loaded. It may be corrupt.”

    Is there anything I can do?

  • 81. Andy  |  March 28th, 2012 at 4:59 pm

    @Ricardo Pollack – From my experience the most likely candidate in such cases is a network driver (ethernet or WiFi depending on if you are using a cables or wireless network). Try if there is a newer driver for it.
    If it was a software problem Skype itself would crash, not no BSOD. You can try an older version of Skype of course just to make sure.

    @Ellie – That sounds like there is a problem with the hard disk that Windows is installed on. The best thing to try is to start Windows from a recovery CD, so you can run a disk check on the HDD.

  • 82. Ricardo Pollack  |  April 16th, 2012 at 12:10 pm

    Hello Andy, I get the BSOS with wireless or ethernet, I have checked and to the best of my knowledge, the two drivers are up to date. I also get the BSOS with other soft phones, like the X-lite.

    Any other suggestions? I will have to buy a new computer if I can’t fix this.

  • 83. Andy  |  April 20th, 2012 at 11:53 pm

    @Ricardo Pollack – If the drivers are up to date, and you have it on all networking devices, it is more likely to be an overall networking issue.
    Try running the “SFC /SCANNOW” command at a command prompt with admin rights.
    That will check and try to fix the Windows system files, so if the cause is in the Windows networking files, this might fix it.

  • 84. Ryan  |  May 22nd, 2012 at 6:23 pm

    Andy, I’m experiencing the same issue that “SS” posted last year. I’m also getting “driver_irql_not_less_or_equal” on the BSOD. Under ‘technical information,’ “Anodlwfx.sys” is listed.
    Some background information: this is a newly built computer. Last weekend, it worked flawlessly while connected to the Internet via a wifi dongle at my house. However, I moved it into my apartment from my house last weekend, and that’s when the BSOD started showing up. I am connected via an Ethernet cable into a router at the apartment (I left the wifi dongle at home because I figured I wouldn’t need it). Thanks ahead of time for the help!

  • 85. Ryan  |  May 22nd, 2012 at 6:29 pm

    I’m running windows 7*

  • 86. Andy  |  May 24th, 2012 at 5:05 pm

    @Ryan – The Anodlwfx.sys file is a driver file for your wireless network dongle. The problem probably occurred since the WiFi dongle is no longer present.
    The best thing is to uninstall the wifi dongle in the device manager, so that the drivers are no longer a problem.
    Not sure if you can do that without the dongle being inserted. But you can try using the option in the device manager to show unplugged devices.

  • 87. Maninder  |  May 30th, 2012 at 6:42 pm

    In my pc iqrl problem shows win32k.sys in techanical information what should i do to resolve problem

  • 88. Andy  |  May 31st, 2012 at 9:55 pm

    @Maninder – the win32k.sys file can cause a bsod in different scenarios since it is a commonly used Windows kernel mode file.
    It could be a driver, so check if you made recent changes or try updating the drivers.
    But a program can also cause the error, so see if it happens with a specific program or during a specific action. If the error happens (seemingly) randomly, chances are it is caused by a device driver. Possibly a chipset driver.

  • 89. Navpreet  |  May 28th, 2013 at 9:46 am

    I have installed Window 8 recently and facing the problem of Irql. I am not able to figure out what the problem is. Whenever I connect my device to Broadband Connection it shuts down by reporting a IRQL eroor . any solution ?

  • 90. Andy  |  May 29th, 2013 at 10:25 am

    @Navpreet – What is the complete error message?
    From your descriptions so far, the most likely cause is a problem with your network drivers. Have you tried updating the drivers or reinstalling them?

  • 91. Cas  |  June 3rd, 2013 at 10:42 pm

    My system error says “tcpip.sys”. Also, I have Windows 8 & it seems silly to be having this happen because I literally got this laptop two days ago and I have already had to reset it to factory settings twice. Please give me thorough instructions on how to fix this! Thanks!

  • 92. Andy  |  June 4th, 2013 at 4:13 pm

    @Cas – Typically the irql not less or equal – error is caused by a device driver, so in the case of the tcpip.sys it would most likely be a network driver (either your ethernet or wireless device, depending on which you are using).
    So try reinstalling or updating the network drivers.
    If that does not help, try disabling your antivirus software, and enable Windows Defender (the default Windows security protection). There have been a few cases where AVG or other AV software caused it.

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