PMDG 737NG with Milano Arrivals Package

Hello allI'm using the 737NG with MGsim's excellent 'Milano Arrivals' which basically gives you a selection of flights into different Milan airports with realistic ATC and chatter. Each flight is accessed via the 'select flight' menu and loads up the default 737, but I'd rather fly it with a PMDG 737. This is where the problems begin.Once it's loaded up, I select the PMDG 737 you get a load of failure flags momentarily and then it settles down and once you've set up the autopilot all is well. After a few minutes though the aircraft becomes unresponsive to commands via the MCP, for example climbing instead of descending and not slowing down for lower speeds set in the IAS window.Is there anything I can do? I really hate the default 737!Ben