I had this happen recently turned out i needed to wipe all traces of drivers and do a clean install.

Driver Sweeper 3.2.0 (Do not update turns it into "Driver Fusion" a pay to do anything crap update)
http://www.techspot.com/downloads/4266-driver-sweeper.html

Remove all AMD reboot if it asks then reinstall 12.10 and App SDK

Hope it helps