I have humanauts problem, on 1280x1024 I can play the game for only a few mins before it crashes (sound crash loop as well), the lower I turn down the graphics, the longer it takes for it to crash, in general, but it always does. If I exit out of the game and go back in, it seems to reset the "timer". Playing on 1024x768 makes it playable at length.
I have a 6600GT, just like humanaut. I have NO IDEA what the hell to do.
And, here's a coincidence, my old Ti4400 ran the original KOTOR just fine too- now it doesn't work either with the 6600GT.
Do your movies have some intermittent pausing as well, which goes away if the movie is long enough?
But here's another thing- my friend has a 6600GT and almost the exact same specs as me (he has more RAM)- and he has no problems.
This crashing also happens with Star Wars Battlefront.