cyrus IMAP deliver failure

[Chack]

Hi,

I am having a problem with cyrus deliver.

I am running cyrus IMAP and postfix. procmail is used to accept mail
from
postfix, then pass it through spamassasin and then it used the cyrus
deliver
procedure deliver it into some user's inbox.

After cyrus IMAP ran for long enough (3-4 weeks), mails start getting
lost.
The mail log contains entries like this:

Oct  6 20:09:52 linux postfix/pipe[15037]: 5E43B15302:
to=<user-4 at mydomain.com>, orig_to=<me at mydomain.com>, relay=procmail,
delay=988, status=sent
(linux.mydomain)

Notice the strange delay time.

The procmail log contains lines like this:

procmail: Timeout, terminating "/usr/lib/cyrus/bin/deliver"
procmail: Program failure (-15) of "/usr/lib/cyrus/bin/deliver"
 Subject: Neuer Kommentar von ThomasBusek
  Folder: /usr/lib/cyrus/bin/deliver user-4

4020
procmail: Timeout, terminating "/usr/lib/cyrus/bin/deliver"
procmail: Program failure (-15) of "/usr/lib/cyrus/bin/deliver"
 Subject: Neuer Kommentar von konst1
  Folder: /usr/lib/cyrus/bin/deliver user-4

4012

As soon as i restart cyrus IMAP it works again.