Thanks for your reply.

I think the 1st infection on 3 March - on the desktop computer - was from a suspicious email that I deleted (in Hotmail). I ran Malwarebytes after seeing a suspicious message to ‘click here to update flashplayer.’ The problems I described continued even after Malwarebytes and Avast scanned and ‘fixed’ the malicious files.

It’s possible that it came from the flash drive though. I use the flash drive everyday in different computers at a school where I teach. Avast only alerted that there was a problem with the flash drive a few days later.

I will run OTL and attach a log.

Thanks!

TW