We have recently faced one issue which got some light as our DA team was not able to search effectively. Searches were either failing or getting stuck, only workaround was to reset the services of Enterprise Vault Journal servers. It was getting worse day by day.
On research & after logging call with Symantec , finally root cause was found:
On 10 August 2015, Microsoft released KB3076895, a critical security update for Windows operating systems. The changes made by this update address a vulnerability in MS Windows operating systems. This update has been found to impact IIS, ASP and .NET functionality for numerous software applications.
Microsoft has released the FIX KB3092627 but unfortunately it is only released for windows 7 & windows server 2008 R2, we are facing issues on server 2008 std edition.
Only solution for windows server 2008 as of now is to uninstall the KB3076895 article from whole EnterpriseVault environment till MS releases the fix.. ( This is what we have done to resolve the issue).