dovecot - Dec 2005 - messages_count too large (1121 > 1115)

I've seen this was mentioned before but remains unsolved.  I upgraded
Dovecot from 0.99 to v1.0.alpha4 yesterday and it rendered my inbox
inaccessible:

Dec 15 00:09:07 sand dovecot: imap(willers): Corrupted index file
/home/willers/mail/.imap/INBOX/dovecot.index: messages_count too large
(1121 > 1115)

I've since moved that inbox away so I can view my new mail again.  The
error has moved with the mbox file:

Dec 15 00:27:41 sand dovecot: imap(willers): Corrupted index file
/home/willers/mail/old-inbox/.imap/200407-200512/dovecot.index:
messages_count too large (1121 > 1115)
Dec 15 00:27:41 sand dovecot: child 83886 (imap) killed with signal 11

This is on FreeBSD 4.8 (yes, yes ... but: "up 687 days" which is quite
nice) all running on local disk.  So earlier suspicions about NFS or MacOS
X are out of the window.

One day I'll move move from mbox to dir format and the problem will go
away, in the meanwhile, I thought it would be good to resolve this issue. 
Let me know how I can help to get to the bottom of this.

- mo

Moritz Willers wrote:
> Dovecot from 0.99 to v1.0.alpha4 yesterday and it rendered my inbox
> /home/willers/mail/.imap/INBOX/dovecot.index: messages_count too large
Dovecot should detect invalid indexes, but this didn't always work in the
past, so it's a good idea to erase indexes when switching versions.