There have been a few reports of OCS services not starting on the front-ends after applying the July 2010 updates. After applying the updates you would see the following error (Event ID 30968) in the Event Log when trying to start the front-end services:
The component Live Communications User Services reported a critical error: code C3EE78F8 (Enterprise Edition Server successfully registered with the back-end, but a stored procedure version mismatch was detected. The service will not start until this problem is resolved. Cause: The database schema and the Enterprise Edition Server were updated by different installation packages. Resolution: Ensure both the Enterprise Edition Server and back-end were installed or modified by the same installation package. The service has to stop.
The workaround is to make sure that you have applied the back-end database update before or right after applying the front-end updates. The database update is NOT part of ServerUpdateInstaller.exe. You can download it (OCS2009-DBUpgrade.msi) from here:
You can get more information on how to apply the database update here: