I checked the forum on this already. Basically, running thunderbird 60.5.2 32bit on a 64bit windows 10 system. Forum moderator recommended rolling back the install and disabling auto update, which I did. Worked like a champ yesterday, but didn't stick- auto updated when I came in this morning back to the 60.5.2 version. There was mention, repeatedly of a 64bit thunderbird which is not available, but would in theory fix the problem, and is very buggy and not ready for release. I need a permanent fix for this, since I need to perform it on all 10 machines that I am maintaining, all of which use thunderbird for email.