When Virtual Vault is enabled for a user, additional worker threads are opened by the EV Client Add-on in order to perform necessary structure (Metadata Cache) and content (Content Cache) updates. When there is a large number of updates requested, it is possible that the worker threads will not close immediately when a stop of Outlook is performed. This was initially in order to ensure no data loss would be possible when forcing Virtual Vault threads to close.
Since Virtual Vault utilizes PST functionality, if the Outlook.exe process is stopped manually, this can cause stability issues with the local OST or Virtual Vault databases.
It has been identified that if the Virtual Vault threads are too busy processing updates, this can interfere with stop requests when closing Outlook. This in turn can cause Outlook to hang indefinitely due to the VV threads not being stopped. This has only been observed in the following scenario:
a. Outlook 2003 installed
b. Large local Vault Cache (15+ GB)
c. Workstation under heavy utilization.
This issue has been addressed as part of the following release:
Enterprise Vault 9.0.3 - Release Details
Enterprise Vault 10.0.1 - Release Details