Can't access Emails

[jimb0s]

I have Windows XP1 Home and Mozilla Thunderbird on Broadband. For a long time now when I launch Thunderbird and click GET MAIL a window come on with the heading: ALERT! "This folder is being processed. Please wait until processing is complete to get messages"
Nothing is being processed and the Windows Task Manager confirms no activity. I therefore would be in for an endless wait.  However if I click the X to close the message window and then click on GET MAIL it may allow it or the message may return. Sometimes a single closure works, sometimes a dozen closures work but today it always returns and I cannot get past it.
I have run my Kaspersky Internet Security V7 (updated daily) regularly but it reports no problems or threats.
I have to assume this is malware of some sort. How can I get rid of it? Has anyone seen this message before?
Any advice would be welcome.
Jimbos.

[evilfantasy]

What is Windows XP1? Do you mean XP SP1? If so why are you not running at least XP SP2?

Personally I would turn off email scanning in your antivirus. It's over kill as anything malicious will be caught by the AV anyway. Plus it seems to be giving you problems.

[Broni]

There is a good chance, Thunderbird is compacting your mail. That process shouldn't be interrupted, or you may lose your mail.
Let it finish.