I have found that if I choose a different aircraft than the one used on the previous flight, the game launches successfully, otherwise the launch is likely to freeze, as described above. This is annoying and a waste of time, but as long as I do this, it works every time. Good luck.
I have recently started using the Console in Developer Mode to see if I can find a clue to the problem, but once the launch freezes, the console freezes, too.