Thank you irocc9555.
I’m unsure what you mean by Windows Restore. If you mean System Restore, I have no idea what date to restore to, since I can’t tell exactly when the condition began, and it did so on multiple occasions. But perhaps you are referring to something else called Windows Restore.
I have done multiple clean reinstalls of the Free version as I described in my post.
Also, when running aswclear.exe in Safe Mode, unless I’m mistaken you only get one choice in the drop-down menu for what you uninstall. I selected one of the choices, and the tool then said it uninstalled everything in the C:\Program Files\AVAST Software folder. Should I run it multiple times for each program?
FWIW, last weekend I noticed avast! had simply disappeared from my machine. The red ball disappeared from the system tray, the icon disappeared from my desktop, and the only link in the Programs list was to the setup file; when clicking on it I got an error message. I thought my machine had been infected with a virus, so I ran Malwarebytes, which found nothing. Neither did avast! when I next installed it. I don’t know if that info helps.
Many thanks.