For no particular reason I tend to use the hyphen character inside filenames (to separate words). When I try to load such a sketch into the arduino IDE (0022), it crashes. Can you either catch the exception and print a suitable error message or - more preferably - allow this to work with hyphen characters. I am also assuming that sketches containing international characters in the name (and of course associated folder) will also cause issues.
I can tell you from experience that if you try to save a sketch while using the IDE and try and use a dash character for the file name, it gives you a bitchy message and tells that it changed the dash(s) to underscore characters.
So it seems that the IDE does not allow dashes in sketch pde file names. Don't know why, I just obey. Kind of like some of my wife's rules, don't make sense but easier to comply then not. ;)