Thunderbird: invalid header

Upon a new install of Eset Smart Security a couple weeks ago, suddenly Thunderbird comes up with the following message:

ALERT - The current command did not succeed. The mail server responded: Message contains invalid header​

This happens when first launching Thunderbird in the morning, once for each new message. Then it happens again when OPENING the message.

I suspect the following issue is the underlying problem, and I think ESET might be causing the header to get corrupted. But that's as much as I've been able to surmise.

http://kb.mozillazine.org/Message_contains_invalid_header

I'm running the most recent versions of Thunderbird (2.0.0.21) and ESS (4.0.314.0) on Windows XP SP3 (all critical updates installed). I have the following TB add-ons installed: Lightning, Provider for Google Calendar, and Zindus.

Is ESS truly the cause of the problem? Any solution in sight?

 

TB user for last 4 years. OS same as yours, however, I do not have your add-ons in TB. My add-ons are: Allow Empty Subject, Quote Colors, and Talk Back. Been ESET user since inception and running v 4.37 and have never encountered any problems. Don't think ESET is your problem, IMO.

 

Try to install ESS 4.0.437.0 (there were fixed a lot of issues since 4.0.314)
4.0.314.0 is pretty old.