Does it hang if you start in safe/troubleshoot mode (hold Shift when launching TB)?

It seems to happen only when I start the computer the first time in the day. Once TB is operating, it seems to work when I stop and restart it. I shut down the computer a short while ago, restarted it, and TB started without a problem. Tomorrow morning when I start TB, I'll try the safe mode if it doesn't start correctly. Thanks.

This morning when I started Thunderbird it hung on two attempts. I started in safe mode, and didn't make any changes. I closed it, then tried to start in the normal way, and it did start normally.

Have you a language pack installed? This seems to have created various problems. Next step would be to disable all your add-ons and then enable them one at a time, checking for the error to occur before adding the next one, which might need a few runs, in your case.. (Might be a short cut of this to look at what you have and see if here are any more likely to be the cause and just try to disable that/those first).

Thank you for that suggestion. The first thing I did was to close a tab of filtered email messages (tagged) that opens with my regular message tab. This morning TB started normally. I'll see how this works, and eventually add the filtered tab back to see if that causes the problem again.

I wanted to report that after a few Thunderbird updates, and at least one Windows update, Thunderbird seems to be working normally, even with the extra tab open. Thank you for the suggestions.