Made a clean re-install of Windows. I would like to have systematically determined which of the three plugins might be responsible, but with malware on board, it seemed best to go straight to a re-install.
Of the plug-ins, I have only re-installed Bongo, on the assumption that since it is a Rhino product, it is least likely to have been infected. So far I have used the freshly installed Rhino for a couple of days with no problems nor malware reports from Malwarebytes. The new installation seems normal, except for one thing:
On the start-up panel, which is a download, the “Tips” section is always left blank.
I would normally ignore this but after the bravo-dog episode, anything odd instantly captures attention.
Thank you for your insights.