Yesterday I was playing CS when I got this thing (happened me to a few times before, on Battlefeild too) where sudenly everything goes jerky, all the players and interface disapear, and all I can see is parts of the scenery, that keeps flashing (as if it keeps redrawing it?), the computer slows down so much you can exit so had to turn off at power.

Now whenever I start my computer I seem to get a black screen for about a minute, then it eventually starts up. Dunno if this is anything to do with the game, but it did start happening straight after.

Any help?
Cheers