What to do if thunderbird stops working:
Thunderbird may be checking for a security certificate. If thunderbird has been left open, it may keep asking over and over.
When the screen below pops up, the best option is to hold down ALT+C for awhile.
Keep holding down these two buttons and that screen will keep flashing. When it’s all down, that screen will disappear.
This is MUCH faster than keep clicking on “confirm”.
If you do not see this window, try minimizing Thunderbird and/or any other programs. Most likely you will then see this window.