New Gaming PC, Periodic lockups while playing TQ:IT

I got my new toy about 3 days ago, see my sig for details, and it's primarily my Photoshop CS3 machine, but I love to burn off steam with a game or 6 so I made sure that I had the horsepower to take care of things.

The only oddity that I find is that under Vista x64 (I played under winxp pro for a full day to make sure that it wasnt the hardware) every 3 or 4 hours during a period of heavier load on the system (say 50 mobs on the screen) my screen will freeze. HDD activity continues and the audio track that was playing when the lockup occured continues to play. However hitting reset, and coming back up and straight into the game yields no problem.

I thought it might be audio related so I disabled the onboard audio in device mgr, and played to lockup again. Now I'm stumped. Anyone with a similar experience?


Thanks,
Colin