Using a Westland Lysander from the Royal Air Force 2000 package, as an add-on in MS Flight Simulator 2002, I have somehow built-in a crash that occurs each time I create a flight at certain specific airports -- airports also added-on from the British Airports series, as well as the standard MS airports.
The flight starts with the Lysander on the runway in normal fashion, then in five or ten seconds the ship jumps up a few feet and smashes down into the runway, burying the landing gear in the runway.
Is this problem likely to be lurking in the aircraft files? Or has something corrupted the MS Flight Simulator 2002 files?
Any clues greatly appreciated.
                                         Lysander77

Many thanks indeed. A most prompt and exceedingly helpful suggestion -- with very thorough instructions!
                            Gratefully,
                                   Lysander77