January 10th, 2009
In some cases USB devices may stop working, in worse cases a complete USB hub may stop working. USB problems are always unwelcome, but if things are working fine and suddenly USB devices do not work anymore or are not recognized, troubleshooting can proof difficult.
If you have tried rebooting, unplugging and re-plugging, reinstalling all necessary USB device drivers, then you might want to try disabling the power management on the USB Root Hubs in Windows. We’ll use Vista as an example, but this method works just the same in Windows XP.
- In the Windows Start menu, select Run.
- In the Run dialog box, type devmgmt.msc and click OK or press Enter.
- In the Device Manager, locate and open the Universal Serial Bus controllers branch.
- You should now see a number of USB Root Hub entries.
- Right-click the first of the USB Root Hub entries, and in the popup menu select Properties.
- In the USB Root Hub Properties dialog box, select the Power Management tab.
- Clear the checkbox named “Allow the computer to turn off this device to save power“, and click OK.
- Repeat steps 5 till 7 for all USB Root Hub entries.
- Now close the Device Manager and restart your computer.
Hopefully the USB problems will disappear after this. If not, you can of course turn power management on again. If the USB problems do disappear, you can try to enable the power management for each of the USB Root Hubs again to save power (especially on laptops and notebooks). By doing it one-by-one you can try to identify the problematic USB hub. Do keep in mind that this requires you to keep your USB devices plugged to the same USB ports!
Microsoft wrote these steps in a knowledge base article specifically for printers, but they can apply with other devices as well. The article also describes the method disabling the suspend mode for USB host controllers by editing the Windows registry, which can be tried if disabling the power management did not solve your problems.
As a last tip to troubleshoot USB device errors, consider powering off your system and completely removing all power sources. That means:
- unplug the power cable when using a desktop computer
- unplug the power cable and remove the battery for laptops and notebooks
Leave the power off for a few minutes and then plug things back on. This has been reported to fix a number of issues with USB devices that suddenly did not work or were not recognized anymore.
Entry Filed under: Device Drivers