httpd: IMAP toolkit crash

[FreeBSD user]

Just recently setup IMP 2.0 RC3 on my FreeBSD machine, and got the
following error on login to imp:

Dec 17 02:28:10 msgsrv imapd[25800]: login: xtremedev.com[216.241.38.65]
cyrus LOGIN+TLS User logged in
Dec 17 02:28:10 msgsrv httpd: IMAP toolkit crash: Bad msgno 5 in mail_elt,
nmsgs = 4
Dec 17 02:28:10 msgsrv /kernel: pid 362 (httpd), uid 80: exited on signal
6

Any ideas on where I can start looking?