We have the same problem in our environment and did a call to Microsoft. The problem is located in the C:\Windows\SoftwareDistribution. If you delete this folder, the updates will work agin.
net stop wuauserv rd C:\windows\SoftwareDistribution /S /Q net start wuauserv
Microsoft told us to delete this folder on the systems. This should not cause any problems, cause Windows is creating the database new. It take more networktraffic, cause he take all the information from the SCCM again instead of the delta information.
