Thanks to both for the replies.
Yes, I have done manual updates every day since the problem started plus a couple of uninstall/re-installs of both the browser and anti-virus.
It was strange in that Bank mode quit working on my laptop and then a day or two later I did an update on my desktop and it had the same issue.
Perhaps there is some piece of software installed on both computers that conflicts with one of the updates though most things I use is pretty mainstream software - MS Office, Zoom, Irfanview, etc.
None seems to have a background process running as seen in Task Manager.