I have already posted this in another thread but I thought I would also post it here just in case it was missed. First off, if you are experiencing crashes then reset your game controls to default and also disable all types of auto saving, since I have done this I have not had a single crash. Also this game does not work well with Supersampling enabled on Nvidia cards as it can cause your FPS to drop dramatically and make the game feel sluggish, so make sure that you don't have supersampling enabled in the Nvidia control panel, either disable it or switch it to Multisampling depending on your preference. 

I hope this helps you guys, it stopped my crashing completely and now I'm really enjoying this game on ultra Settings with my GTX 280. 

Hi i was wondering is overclocking the core and memory going to make the shader clock speed higher too? i was looking into the evga super clocked and noticed it has higher shader clock speed than theregular 8800gt 512mb. or can this shader not be overclocked only by manufacturer?skulper34

If you use the latest version of Rivatuner to overclock you can use it to overclock the shader seperately or you can link the overclock between the main core and the shader together so that as you increase the main core clock the shader will also overclock in sync with the main core. Apparently it is also possible to overclock the Stream Processors using Rivatuner but I haven't tried doing that yet.

http://downloads.guru3d.com/download.php?det=163