Thanks for the suggestion Bob but I’m sure we are all aware of how notoriously slow Avast support can be and I am unwilling to deal with sporadic protection for the next 2-3 weeks while waiting for them to get around to it. Tech Support has apparently not been able to resolve the issue before as this problem has been widely reported for many months. See: nine pages of forum discussion https://forum.avast.com/index.php?topic=196459.120 from February 2017 through June 2017 involving various OS (mostly XP and Vista) and various versions of Avast (both paid and free) leads around in circles. And that is only one example. It is both disappointing and frustrating to say the least.

I guess I’ll just keep researching until I’ve tried everything suggested. But other than wasting a couple days of my time, I cannot continue to use something that will not provide reliable protection.