dovecot - Mar 2006 - Problems with Fedora core 5, Dovecot and Thunderbird

Hi

I am testing FC5 before upgrading my main server and I am getting errors 
with

    dovecot 1.0 beta3 - both the distributed RPM and also the one at ATrpms
    thunderbird (the distributed version which is thunderbird-1.5-6)

I am running both dovecot and thunderbird on the same machine, pointing 
thunderbird at 127.0.0.1 for its imap server.

The symptoms are an inability to access mail - thunderbird just keeps on 
trying and getting nowhere and even if I shut down thunderbird on the 
client, it still leaves processes running that have to be killed by hand.

In the maillog I get

    Mar 29 09:17:25 bree dovecot: imap-login: Login: user=<hartr>,
    method=plain, rip=::ffff:127.0.0.1, lip=::ffff:127.0.0.1, secured
    Mar 29 09:17:25 bree dovecot: imap(hartr): mbox sync: UID inserted
    in the middle of mailbox /var/mail/hartr (8 > 1, seq=2, idx_msgs=4)
    Mar 29 09:17:25 bree dovecot: imap(hartr): file mbox-sync-update.c:
    line 55 (mbox_sync_move_buffer): assertion failed: (ctx->mail.offset
    + ctx->mail.space <= ctx->hdr_offset + pos || ctx->mail.offset
>
    ctx->hdr_offset + pos + have)
    Mar 29 09:17:26 bree dovecot: child 14242 (imap) killed with signal 6

When I point this thunderbird at my main (dovecot 0.99) server 
everything is fine, we seems to suggest that this is a dovecot problem 
and not a thunderbird one.

Can anyone give me any pointers on this please as it's a show stopper 
for upgrading my main server.

Tks

-- 
Robert Hart                                  hartr at interweft.com.au
+61 (0)438 385 533                           http://www.hart.wattle.id.au