some partition managers do not recognize linux partitions.
if m: is now an ext3 partition, find out what partition number it is
if you only have one physical harddrive, its going to be
you can find this out by booting into linux and running fdisk -l /dev/hda
this will tell you all the partitions listed on your system
compare the first line reading
to your /etc/fstab file
if you find one that is ext3 type and is not in your /etc/fstab file, then you can mount it by running
mount /dev/hda# /mnt/music
lemme know if u need anything else or if i am just in a confused rant!