Associate has massive amount of audio files, including those used in Pro Tools, Digital Performer, etc. - as well as project files - on an external FW drive.
These were all used on a native OS9 formatted drive (G3).
Fast forward to last week, and my associate plugged it into a G4 running 10.5 - hoping to open up the old files. According to my associate, the OS was unable to recognize the files - most showed up as an Unix Executable file.
That makes sense, I've seen it before.
However, he tells me that he then plugged the drive back to his OS9 machine, and the files seem to now not be recognized as they were - almost as if the OSX box changed the extensions - without him doing anything. They appear as Unix Executable on his OS9 box.
I attempted to copy a few files and change the extensions (and thus changing the file type - not just changing the display name) with no luck.
Before I suggest anything else, or change anything else, I thought I'd inquire.
Those must be SD2 audio files, right? Despite its popularity in the good ol' days of OS9, support for SD2 was dropped completely, largely because of the issue you"re facing now. SD2 files are very reliant on their ressource forks, which can be stripped way too easily by transferring through a FAT32-formatted system or most internet and network transfers. You then end up with a bunch of files the system can't identify.
It's been quite a while since I've had to deal with this situations but I used to do it almost weekly at one point. One tool I remember using is SD2 Fixer (http://mac.softpedia.com/progDownload/SD2-Fixer-Download-40152.html). It used to work for me and I don't remember any particular problems with it. Once you fix the files, I strongly suggest converting them to a more future-proof file format. Or present-proof, actually...