what are the crashids? https://support.mozilla.org/en-US/kb/mozilla-crash-reporter-tb#w_viewing-crash-reports

Hi Matt! Thanks for taking interest in this problem. Every crash has identical symptoms - here is a crash ID from one yesterday ... bp-59f1829f-471c-40c8-b96f-370a90201013. I have submitted most if not all of the crashes that occur 10-15 times a day. As a temporary work around, I will often quit Thunderbird as the 5-minute time limit approaches, and restart it ... or if writing an email, craft the text elsewhere so that I can quickly past it into a message. Is there some setting that controls what happens 5 minutes after launch?

Here's another crash ID: bp-5a20865e-d4d7-4231-a0e1-65c9d0201014 (many more available if it helps)

The Modules section of the report points to a Bitdefender dll and an NVidia dll. Bitdefender is well-known to cause issues, so I suggest you run Windows in safe mode to bypass startup apps like BD. If TB doesn't crash in Windows safe mode, set BD to exclude the TB profile folder from scanning, and perhaps disable scanning of secure (SSL) connections. Also, disable the Advanced Threat Defense module.

Thanks sfhowes - I tried safe mode as well as two of the tips relating to BitDefender (to exclude the TB profile folder from scanning and to disable the advanced threat defense module) - but no joy I'm afraid. It strikes me as curious that (a) the problem occurs exactly 300 seconds after launch with 100% predictability, and (b) it was also evident in the past two versions - but went away in either the b2 or b3 update. I will continue to try and gather more evidence that might help solve the problem.

Do you have the check interval set to 5 min. in the Server Settings section of Tools/Account Settings?

Hi sfhowes - if you mean the "Check for new messages every xx minutes" no, its not checked. (I prefer to manually check for messages after first reviewing thenm using another software product that allows spam to be deleted before it is downloaded). I have four different accounts, but none of them have automatic mail checking.

I think you will find the bug for the last crash signature you posted is https://bugzilla.mozilla.org/show_bug.cgi?id=1663661

Thanks, Matt! The bug seems to have now been eliminated in the 82.0b3 version.

Thanks, Matt! The bug seems to have now been eliminated in the 82.0b3 version.

You might not be striking it in later versions, but it is described as a race condition. So other changes may have made the winning process change in the new beta, but the underlying cause has not been fixed so the next beta could see it reappear.

Please tell us ... is the problem still gone?

And, had you contacted Bitdefender ?? If so, what did they say?