[Dovecot] Assertion failed in buffer.c

dovecot-0.99.10.5-0.FC2

I have had a report from a user that when accessing their inbox, the connection is suddenly dropped. Dovecot reports the following:-

imap(user): file buffer.c: line 357 (buffer_set_start_pos): assertion failed: (abs_pos <= I_MIN(buf->used, buf->limit))

From searching the list, I found an indication that it is a problem with an individual message. As the user has rather a large number of emails, how can I isolate the message?

Regards

-- Chris Hills IT Services North East Worcestershire College