Hey I was having terrible crash issues, running on ultra high. game would crash even before a map change after about 20-30 minutes of play. I changed the settings to the default medium and made sure all the extra lighting and shadows were off. I played 2 hours straight without a single crash.
I'm runnning win 7
amd phenom quad core 3.7
xfx radeon 7850
8 gigs of something something ram.