On most, if not all, Exchange 2013 CU7 servers the following error appears in the Application Log:
Log Name: Application
Date: 2-2-2015 08:51:51
Event ID: 1039
Task Category: General
Failed to detect the bitlocker state for EDS log drive 'D:\'.
System.Management.ManagementException: Invalid namespace
at System.Management.ManagementException.ThrowWithExtendedInfo(ManagementStatus errorCode)
at System.Management.ManagementScope.InitializeGuts(Object o)
at Microsoft.Exchange.Diagnostics.Service.DiagnosticsService.DriveLocked(String diagnosticsRootDrive)
Apparently the Exchange Diagnostics Service (EDS) tries to determine if Bitlocker is enabled on the volume where the Diagnostics log files are being stored.
I have seen this issue on all Exchange 2013 CU7 servers both in my lab and production environments, as well have other people according this TechNet forums discussion. At time the Error event does not seem to be an actual issue, my guess is that it be safely ignored. Hopefully it will be gone in the next CU...