Yah, alot of people have had these problems, something like
[code:52107]could not locate unnamedsolder\pilot.sks
please restore the file and try again.[/code:52107]
From what I've heard, you have to reinstall the game. I would try removing any custom files you may have first, then if that dosen't work, do a fresh install:
http://mohaa.xgshosting.com/joe/installguide.htm