When I start my flight with the PMDG 737 NGX , it starts cold and dark. This is something I don't want. I can't get on the FMU screen because that's black. Also the default Cessna 172 starts off with the engine running, but it quickly shuts down. Not all my planes are doing this. What do you think is causing this. What steps can I take to get that FMU screen in the 737 to light up so I can go to the " start up in default " to click on to ?

  I do go through the Booster 2013 first to start FSX if that is making any difference. Thanks guys in advance.

Don't have the 737NGX installed right now but I seem to remember that when you click and HOLD one of the buttons (Menu maybe) the FMC will turn on, even when everything is cold and dark.

 

And maybe you saved a new default flight with everything cold and dark? Resave a new default flight with the Cessna and engines running.

Everything is explained in the ngx  introduction manual its well worth reading