Other Symptoms:
If there is a journaling task present journal archiving may stop working as well.
A restart of Enterprise Vault services or a reboot of the Enterprise Vault server is required to get mailbox archiving and journal archiving to work again.
The issue may occur on a nightly basis. There are no other events indicating what the root cause of the issue is.

Full Event ID:

Type: Warning
Event: 40967
Source: Enterprise Vault
Category: Task Guardian
Description:
1694AF55509C3FE4493346AFC41071B2C1012s00evsite - Restarting failed process.

The process has failed abnormally and will be restarted automatically.


Note: This issue may be due to a problematic message. The document properties of the message will have a $File field with a null value. (i.e. " " ).

Solution:
1) To identify the problematic message lower the number of threads of the Lotus Domino Mailbox Archiving task down to 1. Restart the task.
   Perform Dtrace of EVLotusDominoArchiving and EVTaskGuardian. The issue may have to be reproduced a few times to identify a pattern.

2) In the Dtrace search for the following line:

  454169 16:54:39.284 [5228] (EvLotusDominoArchivingTask) <7984> EV-M {ARCHIVEQITEM.EN_US} Note [28be] has not been archived before ...

3) If the same Note ID shows up in all the Dtraces this is likely the culprit. Previous lines in the Dtrace should identify which user mailbox that the Note ID resides in.

4) Next view the document properties of the Note ID and verify that there is a $File field with a null value. If there is remove the document from the user.nsf and attempt another archiving run. If the archiving run is successful without generating an Event ID 40967 then the problematic message has been removed.

5) Submit the problematic message to Enterprise Vault Technical support for further analysis.