imap locking conflict with procmail

Dear Sir,

My imapd seems to have a locking conflict with procmail that causes procmail
not to deliver email to a local user.

Version:
imapd (RedHat 5.1 distribution * OK www3 IMAP4rev1 v10.234 server ready)
procmail v3.10 1994/10/31 written and created by Stephen R. van den Berg
                                
berg(_at_)pool(_dot_)informatik(_dot_)rwth-aachen(_dot_)de
Locking strategies:     dotlocking, fcntl(), lockf()

procmail: Opening "/var/spool/mail/fkam"
procmail: Acquiring kernel-lock
procmail: Kernel-lock failed
procmail: Kernel-unlock failed

This happens when some imap operations are in progress while procmail
attemtps to deliver a mail.

Any hints?

- Francis Kam
Uniforce System Ltd.