1. Download avast! Premier Antivirus: http://files.avast.com/iavs5x/avast_premier_antivirus_setup.exe
  2. Follow instructions: http://www.avast.com/uninstall-utility (Run this tool for all prior installed avast! versions…!!)
  3. Reinstall avast! with the downloaded installer from point 1.
  4. Reboot.