File saved using a different platform you are using, ppc if you are using 68k or viceversa can cause a crash because an error in file format prior of version 1.6.1.
Please note that the program intercepts the eror asking you to close others windows because the program thinks its a low-memory related problem.
If increasing the memory partition/closing opened windows doesn't solve the problem there are possibilitie you are trying to open a old file created on a different platform.
You can select the 'About This Macintosh' command under the Apple Menu in the finder to watch if really is a memory trouble.
Otherwise Flight Master check the free memory before opening a new doc stopping the process before any error can occour and advising you.
File saved using version 1.6.1 or successive are bug-free and you can open it without any trouble regarding platform type.
All files included as example with this distribution are OK.