"Hmm what's this? KB plug fell out completely just now... Damn it does work when it's plugged in ALL THE WAY!"

This was my first thought, but Burdell said that he'd replaced his motherboard and that they keyboard problem was before the mobo replacement and continues to happen afterward. An unplug and replug must have been a part of the mobo replacement.

I wouldn't rule out a frayed cable, though.