[Dovecot] "not listening" notification

[Alan Tam]

Hi dovecot,

My dovecot log shows this:

Feb 27 03:08:38 eta imap-login: Login: sltam [X.X.X.X]
Feb 27 03:09:38 eta imap-login: Disconnected: Inactivity [X.X.X.X]
Feb 27 03:10:32 eta dovecot: login: received another "not listening" 
notification (if you can't login at all, see src/lib/fdpass.c)
Feb 27 03:10:42 eta dovecot-auth: Login process has too old (124s) 
requests, killing it.
Feb 27 03:10:42 eta dovecot-auth: Login process 8 disconnected

Any clues what it means? Recently I have to restart dovecot several 
times a day, after I have report that all users cannot login.

I am running Debian sarge (2.6.8 kernel) with dovecot version 0.99.14-1 
with auth_verbose and auth_debug on.

-- 
Regards,
Alan