If you have an ATI Video card and use the Catalyst Control Center program and you have the problem that CCC won’t start, here’s the solution.
My solution was to clear out the Windows GAC (Global Assembly Cache). In Windows 7, you can browse directly to “C:Windowsassembly”. Sort by “Public Key Token”, then delete everything with the Token “90ba9c70f846762e” (ATI’s key). You’ll obviously need Administrator privileges. No reboot needed either. Reinstalled CCC and it ran perfectly!