Before I logged onto PPRuNe this morning and saw BOAC's and Saab Dastard's cautionary posts, I tried System Restore (have used it a few times over the years but didn't think to try it this time.)
It worked!And since I hadn't installed anything on my computer since the restore date I chose, I didn't lose anything. I would still like to know what caused the problem in the first place (I did run virus and malware scans as soon as the issue started) but I'm glad it seems to be resolved. So, thank you to LastCall and everyone else who contributed to this thread.
Since I have been throwing my computer issues into this forum I have always been grateful for the advice and information I've received...a great spirit of generosity here. It's such a valuable resource and one I appreciate very much.
Latearrival