I have a similar problem. I'm running Windows XP Media Center, and my keyboard out of nowhere stopped working. Windows won't recognize my keyboard at all; I can't even get into the bios before the desktop loads. I've tried uninstalling and reinstalling the driver, but when I go to reinstall the driver, the hardware installer says that it can't find any drivers for my keyboard, even when I have my XP CD in the drive. Windows won't recognize any of the PS/2 keyboards I use with it.