Ok, so I was installing some mods to Star Wars: Empire at War when I tried to open it and my entire computer locked up. Ran 2 virus scans, nothing(It's a reputable mod from a reputable website, "ueaw"). Try opening Fallout 3, same thing. Tried a system restore, same thing. Tried uninstalling the Star wars game, same thing. Tried opening Starcraft II, made it to the main menu but the same thing. This was last night, figured my graphics card needed a break. Wake up, try again, same thing. Tried resetting my graphics card to the factory clocks, nothing. That's all I got, (not sure if this is revelavent but in the boot menu OS selection after windows 7 it says debugger enabled, "Windows 7 [debugger enabled]", right above Ubuntu, and that's never been there before).
nVidia GeForce GTX 560 Ti
8GB of RAM
Windows 7 Home Premium 64-Bit
This is happening to games I have on Steam and games not on steam, WHAT IS THE PROBLEM, I AM OUT OF IDEAS!!!!
EDIT: Just ran a heavy stress test, working perfectly.
DOUBLE EDIT: Computer crashed about 30 seconds AFTER the stress test was completed.