This is a possibility when a Mac will read and write floppies made with its internal floppy drive, but refuses to recognize disks made on another computer, offering instead to initialize them. This, however, was not the problem. The catalog tree header is updated every time you add a file, delete a file, or save changes to a file. The sector containing it wears out before the rest of the disk. When the sector wears out, the disk will be unreadable.
Floppies are fine for transferring data from computer to computer, or for temporary storage.
But if you store a document you access frequently on a floppy, repeated insertions are eventually going to ruin it. Charles Downs is the public information officer and webmaster for the Arizona Department of Real Estate . His first Mac was a 512K which he found on his desk one day when he was a newspaper reporter at the Lake Havasu City Herald. Charles is an associate editor and forum moderator for Ted Landau's MacFixIt pages. He and his wife, Karen, provide troubleshooting and tutoring for Mac users in the greater Phoenix area.