Windows 7: USB Unknown device

This is the first time you have said what is actually going on! Now we can go somewhere with your problem! I have never seen USB devices that "go on & off", and I assume you are talking about the System Tray icon for the alert messages.



Normally when you plug-in a USB device, the alert appears, the driver is installed, the PC is happy. Since you apparently are not plugging anything in when the disruption occurs, then I have to suspect the USB devices you do have, namely the mouse and keyboard, that one or both of these is flaky and/or has a bad cable (and it's unplugging/replugging itself by virtue of a bad connection). If you've tried a new kb and mouse and then uninstalled the "unknown devices" again and still have the problem, then I guess I'd start suspecting the motherboard.

What mfr/model of keyboard & mouse are you using?

I am normally using the keyboard and mouse that came with the desktop. I have plugged them out several times during the last hours and they seem to work fine. Unplugging them have no effekt om the unknown devices. I now use an old mouse and keyboard attached to the ps/2 sockets and and therefor have no usb devices connected. I am still getting the unknown devices.
Motherboard information:

The first thing I would suspect then, given what you have posted so far, is that the USB controller(s) are going bad - cutting in and out. This would be a defect in the motherboard repairable only by replacement.

The same thing could be caused by a corrupted driver or an incorrect driver (chipset drivers).
If you followed the procedure laid out in post #2 then that would have corrected any corrupt driver problem.
You could check the eMachines website for your model # to see if they have any chipset driver updates (laugh here) to try. That would correct any incorrect driver issue.

You could also try running Windows System File Checker, just to be sure some basic driver was not corrupted somehow.
SFC /SCANNOW : Run in Command Prompt at Boot

Below is a snip of a random laptop USB tree. As you can see, the devices that are probably not driven correctly are those intel enhanced controllers, unless you have an nvidia chipset.

Your system may be running with generic Windows drivers but your PC requires specific chipset drivers to function properly.

I agree, and this is easy & quick to do.

Something not so easy, but frobru you should take a look at this:

USB Driver - General Fix for Problems

The premise is that you may have some hidden junk in your Windows system that this procedure will remove, i.e. that might be causing confusion or conflict.

You should make sure your kb and mouse are plugged-in and working, MAKE A SYSTEM RESTORE POINT ALSO, and then "view hidden devices" in Device Mgr to look for any/all "greyed-out" USB devices, and Uninstall them (either click-on and then select the Uninstall icon above, or right-click and select Uninstall).

You have to do these one-by-one. When finished reboot the PC.

Stick with the grey USB devices at this time, but if after you're all done you still have the problem, I would be inclined to open the other categories and uninstall the other "greyed-out" nonpresent devices as well.

Txs again. Tried the guide you linked to twice, but still no good so I just gave the pc to my neighbours son and ordered myself a new Imac. Will run bootcamp on that whenever I am in need for some quality time with win 7 and visual studio.
Again - thanks for all the help- Much appreciated

Hey "no fair" solving the problem with your credit card!

Congrats--I too would like an iMac but can't afford it!

I want to live next to you...