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.
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
16 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… http://www.devicedriverfinder.com/bl…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 http://www.devicedriverfinder.com/bl…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?
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