Hello there Anthony.moffas. We have read your message. We try to help you. Why do you want to use a beta version? Use the 64- bit versions from the software please. Just use the latest full-version of Thunderbird. https://www.thunderbird.net/en-US/thunderbird/releases/ https://www.thunderbird.net/en-US/thunderbird/78.11.0/releasenotes/ Try to use this software https://support.mozilla.org/en-US/kb/rebuilding-global-database Clean your pc before using this all. And use a good antivirus after reinstalling. Greetings Firefox volunteer.

It's a little more complicated than that. anthony, are you still having difficulty?