had a little look around and couldn't find no help, here are some screenshots
only thing that has changed from when it was working fine is i got a hd 7950
Did you update your amd ccc drivers?
I have the same problem now.
I had a working configuration with Windows 8. I used the microsoft drivers for my Radeon HD 5770. I reinstalled windows today because I wanted to try the new amd drivers 12.11. I got the exact same image with xmbc.
I don't want to go back to the microsoft drivers because they have poor performance :/
yes i have the lastest ccc drivers
Rollback your drivers as suggested in post #15 of the linked thread.