Knife Edge/Great Planes have had a few problems with disk compatibility. You could try contacting them and just say that your disk 2 is not working please can you send me another one and here’s my serial numbers to prove I’m legit.

http://12.156.2.54/forums/showthread.php?t=9455

P.S. I speak from personal experience … my disk 2 gives the error mentioned in the thread (I had to copy all the files to another cd and use that to get it to work!)