Screen flipping out...but there is a catch??

Hi,

Sorry to ask for help on my first post but this is driving me crazy.

weird problem with my screen and I'm not too sure how to narrow it down.

I keep getting weird screen flicker and the screen going blank for ages.

So I was thinking it's the gpu but whenever I put on a game, say COD4, the screen flicker goes away.

This can happen even if there are colours all over and it's going crazy...I start a game and it stops...it goes perfect again.

When I come out of the game to the desktop again the screen might still be going crazy.

Nothing is overheating as it's happening when I'm browsing or using word etc....like now.

I just did a fresh install but that didn't help.

Any ideas?

Thanks.

Q6600, 2gb 800mhz ram, ga-p35-s3, 8800gts 320mb, 530w hiper psu and 17" lcd screen