Being fairly new to the game, I'm not sure if this has been mentioned as a solution or not, but it cant hurt to say something... can it?
When I first installed, I set the graphics options to use w buffering [because of the comment that you get better graphics]. Over the course of the next two days [play sessions] I crashed three or four times. After setting this checkbox to off, I haven't had a single crash in eight days of play [including 16 hrs on the weekend].
As I said, this may already have been discussed, tried, and dismissed; but since I haven't seen mention on this thread, I thought I'd mention it.
cheers.