I've installed CFS 3.1 , and Mission builder 3.00513.02 , (and previous beta versions prior to that.) ;......all with the same problem.
The map and everything sets up, but I can't  fly directly from the mission builder.  (It will work if I start the regular CFS3 game, but not from the mission builder).
I click on briefing and start.  I'm assuming this is where the flying initializes, but I don't know.
I click on the question mark and get a blank screen.
Am I doing  something wrong?
Please someone help me.
I had this  for a while , with no results with any version.
I uninstalled this , and re installed it with all the proper updates.