Thanks Rocksteady. I have uninstalled Malwarebytes, but when I try to uninstall Avast Premium it asks for my password. I assume it must be considered a 'protected area' and when I entered my password it wouldn't accept it. I then changed my current password and tried again with the same result. The strange thing is when I uninstalled and reinstalled Avast Premium yesterday it did it without asking for my password. A solution that occurs to me is that Avast Support may know what that password is, assuming one exists. If so, and they could either tell me it or go through a procedure to let me select a new one, I wouldn't need to uninstall all.
Any thoughts before I go to support.