Game and video speed in vista 64

Faulty game and video speed in vista 64

I have a major problem atm that has also happened on another computer a while back. No idea whats causing it and really need some advice please!
Basically after a random blue screen a while back anything playing in a player other then WMP (hiss, spit) runs at more then double the speed. And also its effecting some games I play. I go into a game and the game is running like double speed too. Your char runs everywhere and the framerate and gameplay are like double. I dont get what could be causing this. And yes I tried disabling a core of the cpu... no effect.

Vista 64 ultimate
amd x2 4200
4gb ddr2
7900 gtx

Ok after some checking, video is fine in WMP and MPC, but not in VLC. Games effected include Sup com and Space Siege. What could possibly make all of these run at double speed? I tried installing the latest gfx card drivers. Might try reinstalling directx.

*edit - I have also tried using system restore to a point before the problems started... No joy

Cmon! someone must have an idea!