Windows Instant Search does not find items within Virtual Vault. However, the same items can be found using Windows Desktop Search. This issue may appear intermittently where Instant Search will find items in virtual vault and the stop finding the same items at a later time.
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
Enterprise Vault (EV) 9.0.1, 9.0.2, and 10.0.0 Outlook add-ins running on:
Windows 7 32-bit with Outlook 2010 32-bit
Windows 7 64-bit with Outlook 2010 32-bit
Windows 7 64-bit with Outlook 2007 32-bit