problem with Thunderbird downloading email

Thought I’d posted this already but seems to have vanished into the ether, so once more unto the breach…
Monday early on I accessed my email using Thunderbird, email accounts with my isp using pop3 and smtl and also Google using imap no problems there.
A few hours later my email she no work. Various messages popped up.

After a lot of searching around I discovered that if I disabled the mail shield in Avast! my email worked as normal. I’ve now narrowed it down to scanning incoming mail. If it’s selected I get a message box with ‘an error occurred with the pop3 mail server. Mail server pop.ntlworld.com responded:’ and then a button with OK on it. That message box comes up as soon as I click on the ‘Get Mail’ button, I doubt if there’s time for the mail server to actually receive a request let alone respond. So it looks like the message is could be generated by Avast!, though I’m not 100% sure of that.

I’ve been running Avast! and Thunderbird for a long time now with no problems. Thunderbird has not had any update to it over the last few days so that leaves Avast! as being the likely problem in my eyes. But what exactly? I’ve checked through all the stuff I can think of but can’t see any obvious problems.
Anyone else had a similar problem?

edited a few hours later-
well just before I posted the above I managed to send a test message to to three email addresses, including one to gmail. I’ve just come back in tried sending and now have to disable the outgoing scan to get through Avast!. So in lieu of any answers here I’ll remove avast! and have a go at reinstalling it.

Similar Issue.

Windows 7 Ultimate, Avast Free 7.0.1474 and Thunderbird 16.0.2
I have a number of mail accounts, all IMAP, all but two (to the same server) are SSL. These two won’t work at all unless I disable the AVAST mail shield.

Checking the same accounts with the exact same settings in Microsoft Outlook 2010 on the same computer works fine with the AVAST Mail shield ENABLED.

My Thunderbird has nor worked on my desktop since installing 8. It doesn’t work when I disable mail scan either. I can’t send or receive.

It works fine on my laptop with the same settings. Go figure??