well, I am pretty sure the game loader freeze realy didnt hapen just out of the blue
however, I would reccomend to build right for such cases the alternative shortcut or command file to run the CFS3 in a window mode,
a sample shortcut Target path: "C:\Program Files\Microsoft Games\Combat Flight Simulator 3\cfs3.exe" -window
a sample batch command: cfs3.exe -window
this allows to shutdown the game easier when freeze and/or can fix some problem
the game just remembers what latestly has been loaded and if there are some problems, you should be able to set/load some of the default airplanes back, for a next game restart.
next good thing is to rerun / re set the cfs3config.exe.
finally, all at users AppData folder content under Microsoft\Combat Flight Simulator 3.0 to delete would solve a lot too.