PROBLEM : MBOX remains locked after mail retrieval.

SETTINGS :

SMTP : Postfix, working perfectly to send mail and to receive mail for virtual domain, from and to internet and intranet.
DISTRO : Mandriva 2008.0
POSTFIX : version 2.4.5
VM-POP3D : 1.1.6, run through xinetd, installed from RPM.

VM-POP3D locks the mailbox (user.lock), transfers data, but persists in RAM and does not remove the .lock file. SIGKILL to VM-POP3D doesn't remove the lock. The -t option does not remove the lock after the specified waiting time. Googling for days has not found a similar issue nor a solution. It's not a problem of file ownership, POSTFIX and VM-POP3D run as same unpriviledged user who own the spool mail dirs and the lock files.

I'm stuck with this and can't switch to maildir.

Please help through this.

Thanks.