Thanks for your help so far. Followed your steps exactly again. Still getting the same message trying to use the Avast Uninstall Utility in normal mode and in safe mode. Message is " The stub cannot run the installer/updated executable ‘C:\Program Files\Awil Software\Avast5\setup\Sfx\avast.setup’ (code 0x3)". I’m giving up. I’m going to use System Restore and recover from an earlier restore.
Are you running the installer as admin ?