This worked for me

  1. Download uninstall utility from Avast website here http://www.avast.com/uninstall-utility
  2. Download whichever Avast program you are going to use.
  3. Run the uninstall utility
  4. When it asks whether you want to go to Safe mode SAY YES!
  5. Once in safe mode follow instructions but DO NOT RESTART!
  6. Run you Avast program (mine said that scan utility would run but I didn’t see it)
  7. Reboot into normal mode
  8. VOILA Avast will be working.