xPearse wrote:
I just opened the file directly (floppy PC-98, ISO FM Towns) with a hex editor without extracting. It worked like that for other stuff I've done. Anyhow, it could have been the emulator that didn't play the music right for the FM Towns version.
It seems like you just hex edited a file directly in the ISO image. If that was the case, then as the CD-ROM file system has checksums that no longer matches your modified image and the game crashes because of it. To test if this was the cause, extract all the files from the disc, make your change, then create a new ISO and see if the crash occurs. If the new ISO doesn't crash, then you've figured out the problem. If it does crash, then something else is the problem.