Hi Damian,

the solution is the following. Change the key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL10_50.<instancename>\ClusterState\MPT_AGENT_CORE_CNI and set the value to 1. All keys there should have the value 1. also the one from HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL10_50.<instancename>\ConfigurationState.

This will solve the problem 100%