[Dovecot] help! assertion failed in 1.0alpha4

Hi,

I've been getting this bug in 1.0alpha4. It happens every time the user checks his Inbox. I'm using mbox btw. Can I get any hint on why this is happening?

Dec 9 09:08:39 lasige-serv dovecot: imap(pjsousa): file mail-index-sync-ext.c: line 155 (get_ext_header): assertion failed: (memcmp((char *)(ext_hdr + 1), ext->name, strlen(ext->name)) == 0) Dec 9 09:08:39 lasige-serv dovecot: child 18309 (imap) killed with signal 6