Okay, here's an update: my home system continues to work well. Did the Troubleshoot change at the mirror system; that, too, is now fine. I have a few people to whom I recommended Avast! and I will pass this info along to them.
I've always said I like Avast! because the people who made it and supported it were honest and determined. You guys have proven that. My thanks to all of you.
mycroft69