A lot of people are having this problem with 8000 series cards. I had the same issue and my card is an 8800GTX and I'm using Win7 32bit. The only way to fix it for me was to turn off shadows and instead check the two options next to shadows on. It doesn't look as nice but its the only way to play the game. Too bad they won't fix this.
I am not sure if you are crashing for the same reasons as me, doesn't even sound like you are getting to the game.
