Have you ever received a message of "The remote session was disconnected because there are not Remote Desktop client access licenses available for this computer"? or maybe something similar with Terminal Server instead of Remote Desktop in the message?
I have, I have seen this with Remote Desktop connections, Terminal Server connections and Citrix connections. The solution is always the same.
Important, before modifying the registry, always export the section you are modifying so if something goes wrong you and re-import it.
Note: This is a client side issue, perform the following procedure on the system from which you are connecting, not the server you are connecting to.
Delete the following key and it will most likely correct your problems.
Note: On Server 2012 systems, you may need to run Remote Desktop client, mstsc.exe, as administrator for the system to have the privileges needed to re-create the key.
If you know the purpose of this key, beyond "Microsoft Licensing", please comment and let me know.