I've been running Thunderbird with four gmail accounts for years, but it suddenly stopped working yesterday around 11:30 AM Pacific time.
This must be related to a ESET update.
I am running Nod32 Antivirus 5 version 5.0.95.0
Thunderbird will not receive gmail. It will send, but report an error saving to the Sent folder.
This is a CRITICAL problem!