Have you encountered Event 8390 in the Enterprise Vault (EV) Event Viewer?
Event 8390 can occur in EV for numerous reasons with many accompanying event IDs. Before you create a support case with Symantec, the solution you seek may have already been documented.
We have created a digest that illustrates some of the frequently encountered occurances. The article contains links to 14 Tech Notes, which document detailed information on diagnosis along with the applicable solutions.