Update: This has been fixed in Exchange 2010 SP1 Rollup 3
We recently ran into an issue when trying to apply the latest rollups for Exchange 2010 SP1. We never had this problem with the rollups on Exchange 2007.
What happens when the update fails, it rolls back, but it leaves all dependent services in a “Disabled” state (when it fails it does not reset its services back to the way they were, which is very bad). To find out which services it changed, the easiest way is to look in the System Event Log and see which services were modified.
This issue occurs when you have the “PowerShell Execution Policy” defined in group policy. You can find this policy in the Group Policy Management Editor under: Computer Configuration > Policies > Administrative Templates > Windows Components > Windows PowerShell > Turn on Script Execution.
The only workaround I could find is to temporarily disable your GPO that configures this policy on your Exchange server (or exclude your Exchange servers from the policy). After the patch has completed successfully, the policy can (should) be re-applied. Hopefully Microsoft will fix this for future rollups.