well, if you know your way around system files and have the os cd, then go into safe mode and into DM and delete the PCI bridge and reboot. It will redetect everything. Also, before doing this check the bios and disable/re-enable USB. Also, may want to (if plugged in back) enable the front USB ports in the bios (if you have front panel USB) and plug it in there to see if that works. Also, if you're using a keyboard cable extension or anything between you and the system, remove it and have NOTHING in between the kbd and the system. No extenders, USB hubs, or anything.
If you argue with an idiot he will drag you down to his level and beat you with experience.
I am not a fast writer.
I am not a slow writer.
I am a half-fast writer.