Well I don't use windows 8 but I would assume there is some sort of safe mode can you boot into that (with networking) with out any issues ?
Here is what I did. I booted in safe mode and tried to uninstall the drivers but it wouldnt let me. Then I restored the pc and re installed everything but this time I used the latest catalyst beta drivers. As soon as the drivers finishing installing 20 seconds later the comouter shut down. What else can I do? maybe twitch the voltage of the card once in safe mode? I dont know if that makes sense.