Crashing at random intervals.

[Odinn]

First off I have done a search and it has proved fruitless therefore i must find a way to fix this niggling problem...

Problem: As title says I can enter the game fine but at any random point, whether it be after 5 minutes or 30 it cashes unexpectedly and quite randomly.

Game: Just the regular no mods.

Setup: Q6600, 4gig Ram and SLi 8800GT's, Vista Ulti 64bit

Attempted Fixes: Reinstall, Cleared the registry and installed again to no avail. I have a OC'ed computer and run many hardware checking components so I do not believe it to be hardware, But I have tested none the less. Tried running both from Steam and directly from it's .exe
Have given the PC a rigorous run down of scanners, AVG, Spybot, Malwarebytes, Blacklight etc.
Am currently re-downloading the install file from another mirror but I am at wits end, specially since I want to play   

Oh and thanks in advance if you can help

EDIT: I should let you know it crashes the entire computer not to desktop but a full reboot.

 

[Archonsod]

Try disabling SLI and running on one card, see if it still crashes.

 

[Odinn]

Winner, I disabled Sli this morning and it worked, just now reading your post 
Thanks for your help, its a great game and I would have been incredibly frustrated had it not worked