Thunderbird was working fine last night. It won't load this morning.

What is your anti-virus software?

What is your anti-virus software? Eset

Anti-virus software is often the culprit when Thunderbird is not responding. Specifically ESET has been known to cause problems with Thunderbird. https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues#ESET These are some generic suggestions to avoid problems with anti-virus software. Create an exception in your anti-virus software for the Thunderbird profile folder, so that the anti-virus real-time scanner will not scan it. https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#w_how-to-find-your-profile Don't let your anti-virus software scan incoming and outgoing messages. Don't let your anti-virus software scan attachments. Don't let your anti-virus software intercept your secure connection to the server. Remove any add-ons your anti-virus software may have installed in Thunderbird. Keep it working. https://kb.mozillazine.org/Keep_it_working_-_Thunderbird And last but not least, backup your Thunderbird profile on a regular basis. https://support.mozilla.org/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile

Thank you. I will ask the support people to try this. I SOOO appreciate your help. fingers crossed that it works.

An easy test to check if AV software might be involved, is start Windows in Safe Mode