Turning off Directx11 has seemingly fixed my regular crashes.
Shame because now I get stuttering, load times are up, and it doesn't look as pretty .
There seems to be an issue with people who have nvidia 5 series cards, especially over overclocked ones using direct x 11. There are a few posts over on the steam forums and loads more on the eidos forums.
I used to get a crash every few hours but the further I get into the game it just crashes more often (finishing off China level at the moment) I can max the game in DX11 and get a solid 60FPS and my temps are fine, the my GPU never goes over 73 degrees.
They really need to patch this as the DX 9 version, although doesn’t crash runs terrible, stuttering and 2 seconds freezes are common