To unprotect Rex Nebular look for the following bytes
     in the NEBULAR.EXE file    8D 86 24 FF 50 9A 6C
     replace with.........      EB 02 7B 7D 50 9A 6C

     I used PCTools 4.2 to find these bytes. This combination
     only appears once!

     As always make a backup copy of your original file.

     Enjoy the game.........

     Zippy