The problem continued this morning so I rebooted, opened TM found no Vivaldi in running processes. Opened Vivaldi then exited, waited a minute or two, opened TM and 2 Vivaldi running in processes. Ended those processes (luckily it worked for me), closed TM and opened Vivaldi again...then exited, checked and both were back. I opened Chrome, to see if something similar was happening with that browser, then exited, checked and no Chrome in processes. BUT...very odd....the next time I opened Vivaldi and exited, then checked Task Manager, all instances of Vivaldi in running processes were gone and things appear normal in that regard. Now just need to check it with my research site to see if notes and changes will be applied in this snapshot.