I turned shadows up to medium and no more crashes, but it needs more testing.
You must find what is the problem, i really dont want to play with shadows on medium or high, it eats around 20 fps :S
AMD Phenom II X6 1055T 2.8~
4GB Ram
AMD Radeon HD 6870 1GB
Windows 7 64x
Settings in game:
1400x900
V-Sync: Off
Detail Mode: Ultra
Character Model: Ultra
Texture Quality: Ultra
Shadow Quality: Medium
FX Quality: Medium
Anti-Alising: Low
Post Processing: Ultra
Lighting Quality: Ultra
Foliage Quality: High
Bloom: On
Motion Blur: On
Light Shadfs: On
Ambient Occlusion: Off
Framerate Smoothing: Off
One Frame Thread Lag: On