Almost immediately upon starting the prologue, my game began freezing up (video stops dead but ambient audio continues); when I control-alt delete and then pop right back in the Witcher 2 window, the game runs fine for anywhere up to 5 minutes or as short as 10 seconds before freezing again.The initial freezing will begin after around two minutes after loading the game, and after the first freeze, lots of bizarre visual artifacts start flying around and freezing will typically accelerate.

I have literally been forced to do this con-alt-del move several hundred times. I have tried adjusting every setting, I have updated my graphics drivers several times, and I have tried reinstalling twice. This issue is nearly game breaking, with freezing happening with extreme frequency and at the most inconvenient times. I am really at a loss as how to keep trying to attack the problem, so if anyone has any ideas it would be greatly appreciated.

My system

Windows 7 64-bit
i7 870
8 gigs ram
Geforce GTX 285