When I start up FSX and load 737 ngx the first time everything works fine. If I want to change the airport location or just simple restart the flight the cockpit instruments dont work, the engines are out and the only way to restart is to quit FSX and start all over again. Is this a kown problem? Is there a way to fix this?

Its probably smart to restart FSX and reload the NGX if you intend to change locations after loading the NGX, or any other complex add-on for that matter. Its never advisable to do so from inside the cockpit.

thanks, I'll follow that recommendation

My pleasure :-)