First make sure each music file has exactly the proper3 character
extension at the end of its filename:
-- each one preceeded by a 'dot' (period), of course.
If that's correct and the problem remains, try using a utility
(like FileInfo or FileXaminer or File Buddy) to verify and/or
assign the proper 4 character
type and creator codes.
Did you know about this under OS9? Anyway, the creator
code for iTunes is 'hook
' and type codes are as follows:
extension type code
.m4a 'M4A '
.m4p 'M4P '
Do NOT include the quotes ('), and note that there is aspace
character after the last two.