So... I simply opened my PC and used one of the canned air thing on the cooling fans and removed the hard drive that was likely to be the culprit, and wouldn't you know it, the PC is acting like it was brand new!
My only concern is the hard drive, it says is has no format now, so the data on it is lost... All I had on it were games and Mirc.... So it's not that a big loss... :P
UPDATE: I'm fairly sure the real culprit is Neverwinter Nights 2, the problems started when I installed the game and disappeared when the game was lost in the hard drive failure...
And almost started again when I reinstalled the game! The PC crashed, and couldn't find the main hard drive! When I finally managed to get back I uninstalled the bloody game, and from what I've heard, I'm not the only one with problems, but I do seem to be the only one with problems this big... :/