Markslayer

ok so I have the sony Fm Walkman MZ-NF520D, I got it a few years ago with and earlier version of Sonic stage, but I lent it to someone and never got it back, now when I try to use my MD player on a new computer It asks do you want to install software for this device and it can't find anything. and the player will not work, I managed to get a later version of Sonic stage but it didn't seem to work.. how exactly do I fix this problem? Thanks