[Dovecot] Assertin failed on mbox after upgrade to 1.0rc10 [Was : Re: Urgent - Inconsistent Inboxes]

Now I upgraded my 0.99.14 server to 1.0rc10 and just what I feared has happened :

dovecot: Oct 19 09:06:05 Error: IMAP(oekov): file mbox-sync-rewrite.c: line 405 (mbox_sync_read_and_move): assertion failed: (need_space == (uoff_t)-mails[idx].space)

on one mailbox; regerdless of the client (TB or OE). I looked into the Mailbox but cannot find anything special at a glance. In the mailing list I find this error only witzh a CVS version over a year old.

Any hints ?

Yours, JC