[Dovecot] child <pid> (imap) killed with signal 6

[Per-Stian Vatne]

Linux <hostname> 2.6.8-1.541 #1 Wed Sep 1 18:01:46 EDT 2004 x86_64
x86_64 x86_64 GNU/Linux

dovecot-0.99.11-1.FC3.3

I'm struggling with some new problems after an update from the devel
tree of Fedora. Have been using dovecot since FC1 test-something, and
latest working was couple of updates after FC3t2 (2.91 + devel
updates). Tried downgrading with no luck, and can't figure out what's
wrong.

Setup is very standard Fedora, all defaults I guess, using postfix and
Maildirs, and dovecot for imap access.

What happens is when logging in and authenticated ok, the connection
is dropped. To illustrate I've connected directly and showing the
(verbose) output:
(commands)
[xxx at xxxxxxx ~]$ telnet localhost imap
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
* OK dovecot ready.
x login imtest <password>
x OK Logged in.
Connection closed by foreign host.
[xxx at xxxxxxx ~]$

(log)
dovecot-auth: Oct 02 14:59:32 Info: Login process 7 connected
dovecot-auth: Oct 02 14:59:32 Info: Login process 7 sent handshake: PID 10816
imap(imtest): Oct 02 14:59:40 Panic: Trying to allocate 0 bytes
imap-login: Oct 02 14:59:40 Info: Login: imtest [::ffff:127.0.0.1]
dovecot-auth: Oct 02 14:59:40 Info: Login process 6 disconnected
dovecot: Oct 02 14:59:40 Error: child 10818 (imap) killed with signal 6


I've looked around on the web for this error, can't find anything
except problems reading index files, so the imtest user is a newly
created user which have received one single text message, Maildir is
created ok and can be read using mutt or something.

So problem is for all accounts, both new, old and empty. Would be
guessing some sort of permissions problem but should be running mostly
as root in default mode? And the dovecot user seems to be ok and
working, directory permissions are corrected at startup if it's wrong,
and so on...

I'm not an expert, might be something trivial, but cannot figure it
out by myself or Google so mailinglists are next. Let me know if I
should send some more information about the system.

Thanks,
Per-Stian