Computer seemingly spamming a keypress of some sort.

My computer is spamming an unknown key, it doesn't show up in text or anything, but javascript detects it, and it prevents my screensaver from coming on. It also interferes with flash etc. It's not malware it would seem: http://forums.majorgeeks.com/showthread.php?t=201066 already had that checked. I'm not sure what my next step is, but I've been trying to find anything at all that could be doing it, and I see nothing.