Lotus Notes Mailbox corrupt

Hello everybody

I got a problem with my system again. I am running Lotus Domino 5.0.8 on a Windows 2000 Server. My clients are running Lotus Notes 5.0.5. (Yes, I know its stoneage but i am going to upgrade to 6.5 soon, probably during christmas)

The Domino server works great all day, but at the strike of 04:00 when thee server starts compacting, the mail.box gets corrupted.

A few lines from the Misc log:
06.11.2004 04:00:02 Router: Shutdown is in progress
06.11.2004 04:00:02 Router: Beginning mailbox file compaction of mail.box
06.11.2004 04:00:04 Document NT0055588A in database D:\Lotus\Domino\Data\mail.box is damaged: Document attachment is invalid
06.11.2004 04:00:04 Router: Unable to compact mailbox file mail.box: 03:F5
06.11.2004 04:00:04 Router: Completed mailbox file compaction of mail.box
06.11.2004 04:00:05 Router operation resumed.
06.11.2004 04:00:05 Router: Mailbox file mail.box is corrupt

This results in mail.box getting read-only, and users can't send or receive mail. The only solution I have seen is to restart the Domino server.

This started abtout 2 weeks ago. I entered mail.box and deleted all dead mail stored there. But still this happens, at least 4-5 times a week. I see why it happens, but my question is how can I prevent it from crashing my Domino server??

I guess it is because of the same problem some of my users have been getting mails they cannot open. They get an error message saying: "The object store note that is used by this note was not found. Run the object store collect task on this database".
Is this because of the mail.box keeps getting corrupt? How do I run the object store collect task on a database??

Have a nice sunday, everyone!