This has been banging around various OS10 forums for a few weeks. Just came across this myself but on only one of our Tiger G4 machines. All the rest work fine. Seems to have happened immediately after a software update but that cannot be certain.
In my particular situation, the burn folder designation/extension cannot be removed from the disk's image at all since it was burned that way. Every disk that gets inserted comes up with ".fpbp" tagged onto it and this cannot be deleted. Not at all, no way. I've tried everything I know of to remove that extension.
Since the disk knows it is a burn folder that is located only on the desktop of its host computer, no other computer will open it. And no computer incapable of seeing burn folders will recognize the disk as anything but useless media.
It's all quite confusing.
This is my standard sigfile so do not take it personally: "For crying out loud, read the freakin' manual."