When you install new drivers, try to first make sure the previous version is properly and completely uninstalled.
Try using a drivercleaner like "Driver Fusion", download and install it, then:
First, go to control panel -> programs and applications -> remove all AMD catalyst related programs and drivers, then reboot.
After your reboot, use Driver Fusion to completely remove any remaining ATI/AMD related files and registry entries, then reboot again.
Then install the new Catalyst 12.11 beta drivers (12/3/2012) -> reboot.
Finally, install the Catalyst Application profiles 2 (12.11 CAP 2, 12/3/2012) -> reboot.
This way you have made absolutely sure everything has been properly installed and there are no residual driver conflicts.