SSL problem with Thunderbird

Apologies if this is answered elsewhere. Seen SSL issues but not this specifically.

Have AVAST 2014.9.0.2011 & Thunderbird 24.2.0 (email client).

A couple of days ago I had to disable SSL scanning within the Mail Shield, because TB wouldn’t send any messages - it just kept trying to send them until I cancelled the operation.

This has only recently occurred. Has something changed somewhere ??

Thanks.

have you checked the FAQ section http://www.avast.com/en-eu/faq.php?q=ssl#searchForm