dovecot stops working (partially) in FC3

[Paul Michael Reilly]

Dovecot IMAP (partially) stopped working on mail server within the
past 8 hours or so.  I have checked and double checked logs, searched
google, tried multiple clients, rebooted and have come up empty so I'm
looking for some suggestions on how best to troubleshoot this problem.

The complaint from IMAP occurs when I try to force a read of INBOX
using the "Get Mail" tool button using Thunderbird.  Thunderbird
reports that the IMAP server has declared "The current command did not
succeed: The mail server responded: Invalid messageset: -2147483648".
Other folders can be read fine.  The existing messages in the INBOX
folder are viewable, fileable and deletable.

The RPMs are uptodate although I've seen nothing on the Fedora mail
lists to indicate a problem.

TIA

-pmr