first off, reformat your player following these directions if you havent already...
http://teekobeach.com/howtoreformattheplayer.html
if you have a hacked player, the playing issues your having will develop.
try that first and find out how much real memory you have and then open the "removeable disk F" or whatever it is, create a folder called "Music" and then upload your songs to it and go from there