[THIN] Remote Desktop Users

Ok suddenly users on one server are not allowed to log in because the server says they do not belong to the remote desktop user group.  I have check the RDS group and the correct groups belong.  I have checked ICA-TCP permissions and they are good.  I have checked user rights assignment and RDS belongs to the allow logon to TS.  I cannot see any reason they should not be able to login.  Anyone have any ideas?