If you REALLY wanna fix it, you need to rip that crappy heat sink off of the gpu and replace it with something decent. Get some good heat paste and a better heat sink off new egg and set it straight!! That damn GPU can heat up enough to fry an egg on it with their half assed cooling efforts.
Wow. Just a few days after mine! I was thinking about doing the same thing, but it sounds like mine was just fried to death. I wasn't feeling like messing with it or fucking with Microsoft, so I just went out and bought a new one.