[Dovecot] dovecot deadlock with procmail

[kunal verma]

I m using dovecot 1.0.7. I m having problems in mail delivery to my mail
server locally.
When a user sends a mail few mails are in mail Q for longer period of time.
The local delivery agent(*procmail*) is trying to deliver the mail at
regular interval but it is unable to deliver.
But as soon as I *restart* *dovecot* the mails in the Q are delivered
immediately.
I suspect it is because of locking of *mbox* file of users by dovecot.
How to overcome this problem as mails are some mails are taking hours to be
delivered??
please let me know the solution.

Kunal Verma