I also receive:" The virus scanner engine cannot launch: try please to reinstall the application, or consult the support "message on our new macbook. I am a mac newbie and recently brought all the files and programs including a trial version of avast over to the new machine from a time machine backup on a different Imac. On the new macbook the avast preferences are greyed out as well. I tried removing and reinstalling avast with no success. I successfully navigated to /Applications/avast!.app/Contents/Resources but could find avast!.app or~/Library/Application Support/com.avast.MacAvast/ to try the fix. Thank you BK