I went to programs and features > Avast > (right click) Uninstall > Update. I found out there was a new update (version 19.3). It installed & message showed I need to restart computer. I did & U.I. seems to work now. I have updates set to "automatic". Some how when I started computer earlier this morning, Avast must have "hung"? I suppose I need to change update settings & manually check soon after starting computer every time? That is a time consuming pain....
Thanks for your prompt replies!