Is there a limit to number of mailboxes in cyrus

Tue Sep 6 08:44:27 EDT 2005

Hi,
  I have a cyrus server running linux RHEL3 with around 4000 mailboxes.
( Single machine 2GB Ram dual-cpu with RAID ).
Most of the users (90%) use pop to read their mails

The problem is with frequent corruption of mailboxes. I have to
reconstruct the mailboxes and then runs fine again.

Is there some tuning I can do to my server or just that I cant add any
more users now 

thanks
Ram