Dodgy Audio in games

Hi, when im playing games the audio keeps cutting out and coming back in. Its fine in music playback and was fine yesterday.

Today i've been playing Farcry and NFSU2 and its been a problem in both.

Hardware is:

2.26Ghz P4
Radeon 9800Pro
1GB Crucial RAM
Soundblaster Live 5.1

Think thats all you need to know

Im wondering if its a heat related issue? GPU maxxed out at 69.9C just now whilst playing NFSU2, didnt have anything monitoring CPU temp.

I put a duct on the CPU the other day, do you think its the soundcard getting overheated?

Ben