I have the exact same problem. What helps for me is putting it in compatibility mode with Windows XP Service Pack 3, although which one to pick might differ for you. It could be something to look into as it allow me 6 hrs playtime before I'm in danger of a crash.

Try:
- Disabling Internet before you play
- Disabling antivirus/firewall

I have the same problem and this lets me play for a while as long as I don't do anything crazy.
Also with the DEP you might want to just check the "Enable for Windows products and services only" box instead, it works better for me.

Hmmm... well one thing that happened for me is that at first the DEP prevention didn't work even though I added all the .exe files, so I just filled in the "essential Windows products and services only" bubble instead. It makes your computer a bit more vulnerable but if you think you're still having DEP problems its worth a shot.

I have the same problem and these solutions seem to help:
- Turn off antivirus and firewall when you play
- Turn off network capabilities when you play, if you don't already.
The game still crashes for me, but only after a couple hours instead of minutes.

Edited because you already turned off DEP.

Also, from what I understand it appears to be a video driver issue so you might want to see if you can update your driver. Since the crashes come without warning, I keep my phone near to play games while I save every 20 min or so.