Not all music players can read CDRs. Even some which can may still not be
able to read CDR-Ws. Additionally, depending on how you copied the files,
you have have ripped the files and copied the music into a different format
which a CD player cannot read. For example (and this is only one example of
how the problem can occur). Windows Media player will copy music files from
a CD, but it will convert it first into a .wav format, then into a ..wma
format when it is downloaded onto the hard drive. Then when the user copies
the files to a CDR or CDR-W, Media player converts the files back to the
original format before copying it to the CDR or CDR-W. If a user decides to
copy some old music files which are currently on his hard drive which were
previously created through Media Player, they can't just copy the files
straight onto a CDR or CDR-W and expect any CD player to be able to read the
.wma files.