I had a similar problem with Flight Simulator 2000. At some day it also
produced a fatal exception at startup. I presumed it had been an error in
the registry.
My solution:
* Rename gp3.exe to something other, like gp3-test.exe
* Start gp3-test.exe
* If it works, rename to original file name.
It worked for FS2k. Why not for GP3?
:-)
Alex