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"Unknown Device" Problem for several USB devices

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by alumsdaine

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My printer and external hard drive (both USB) now come up as "Unknown Device" in Device Manager. I have used them both for months in the past with no problem on my Windows XP desktop machine. When I check "Properties" it says that "No drivers are installed for this device." I have tried turning the devices off, unplugging them and plugging them in again (in the USB ports both in front and in back of my computer), to no avail. A few more notes:
-I have uninstalled and reinstalled the printer software, and nothing changes.
-I started up the computer in safe mode, and both "Unknown Devices" still showed up in the Device Manger.
-The devices start up fine when plugged into my other computer (a laptop, also XP), so I'm pretty certain that the problem is not with them.
-Several flash drives also are "Unknown" when plugged in. Oddly, I have one flash drive that is identified properly.
-I have performed a "System Restore" to roll back to a state where the drivers worked, but the devices still show up as "Unknown".

Does anyone have any suggestions on solving this vexing problem?

4 replies

by mayhem1969

whether you've tried removing these devices from the device manager and uninstalling all associated files and software, booting up and reinstalling the devices. If not, you might give that a try.

Also, you may have downloaded a recent update that interferes with peripheral operation. You might also check any firewall or antivirus software that may be interfering with the device operation.

If all else fails you might try an in place reinstall of windows XP.

by tintoman

Thats good advice but also consider that if your devices are plugged directly into the PC usb ports, the motherboard could be failing, on the other hand if you are using a usb hub which is not self powered you will need to change it for one that is self powered.
If you already have a self powered hub that could be failing.

by alumsdaine

Thanks for the suggestions. I have tried the removing and uninstalling. I have discovered (through another old message board posting) a weak fix - when I disable the USB Enhanced Host Controller, it identifies my devices again. I believe that they only operate at USB 1.1 speed, though. But at least I can print!

I was also told of a hotfix:
http://support.microsoft.com/kb/920875

It doesn't seem to fix the problem, though.

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