For additional research to determine the cause of a failure when using Enterprise Vault with Exchange 2007 Outlook Web Access (OWA), it may be necessary to enabling diagnostic logging.  Follow the steps below to enable logging on Exchange 2007 OWA:

1. On the Exchange 2007 Client Access Server (CAS) that the Enterprise Vault extensions were installed on, open <exchange server install path>\Exchange Server\ClientAccess\Owa\web.config

2. Under the <appSettings> section, add the following line to enable logging and then save the file:

<add key="EnterpriseVault_LogEnabled" value="true"/>

Reproduce the issue and then browse to the C:\Program Files\Enterprise Vault\OWA\Logs directory and send in the log that was created by the reproduction (a separate log is created for each OWA session of each mailbox per day). Logging may then be disabled by removing the created line from web.config and then saving the file.  

Notes:
   a. Alternatively, changing the value="true" to value="false" will disable logging.
   b. If a DTrace of the issue also needs to be captured, please postpone reproducing the issue until that has been configured.