Hi, they've just released a new set of drivers:
Customer Support: Downloads
You could try what you suggest with your mobo although if it's disabled in the bios it should be ok. I'm intrigued why your getting the lock-ups after 2hrs and not before. So please provide the following info...
What game does this happen in?
Does it happen when playing any other game or is it 'exclusive' to one game only?
If it's only happening in one game then I'll bet that it's the graphics driver but anyhow let me know the above..