You'll have to check and see what your situation is, but in general USB devices shouldn't be unplugged and plugged back in without using the "Safely Remove Hardware" button down in the right hand end of the Start bar. (Which may be tricky to do if it's your mouse that's not working?) Some USB devices don't show up there, and in that case you're probably okay unplugging and replugging, but with ones that do show up, if you don't "unhook" them before you disconnect, the machine thinks its a new device when you plug back in, and creates a new hook for it.

You can end up with a half-dozen extraneous USB Hubs/Ports in the system that aren't doing anything, except eating cycles to check and see if the device has come back.

If a device has worked, you can uninstall the driver, reboot, and be reasonably sure that PnP will reinstall the right driver when it detects the device during startup. If you uninstall all of the USB hubs/ports and reboot, the reinstall should be just the ones you need.

The clinker is, if you're using a USB mouse, when you uninstall the USB hub it's running off of, the mouse will quite - and may it be the last thing to come back after you reboot, so you need to be prepared to "do it the hard way" (keysboard only) to shut down and restart.

Start|Settings|Control Panel, Double Click "System," Click the Hardware Tab, Click Device Manager.

If you don't have an obvious excess of USB things, just exit; but if it looks like too many, click each hub and select uninstall, and when they're all gone, see if you can figure out how to reboot (if you've accidentally turned off the mouse, like I did about a half hour ago).

I actually only had one extra port that apparently popped up because I changed an existing connection to a different hub with the system shut down, and when I booted it added a new port but left the old one there. It lost an external USB hard drive because of it, but all's well once again.

I was also reminded during my little minormaintenancesaga that leaving a CD in the drive can significantly slow down the boot. A disk in another drive that's in the boot sequence (in ROM) usually will get an error message that there's no boot sector; but WinXP usually ignores a non-bootable CD - after it's searched the entire CD (or DVD) to be sure there isn't startup info on it. The search can add 10 or 20 seconds(?) to getting started up (at least on my old machine, and probably depending some on what kind of stuff is on the CD).

John