I have spent a fruitless afternoon with all sorts of gremlins and weird happenings with FSX and the Captain Sim. All began when I used the Capt Sim cold n dark and then relocated it to Avalon in Australia, then I changed the fuel and pax loads. From there on in nothing I would do would get the no 1 engine to start and so think I did not understand the systems from there on in when I tried to load another flight windows decided they were all the same and no matter what aircraft I would load it would not start the engines. Even the Trike would not start.

Solution you guessed it, shut it all down, reboot and start all over again.
Hrummpph #$%@!! :-/