Bipsen

Hi, I just bought a NW-HD5 and have quite large mp3-collection, that i would like to transfer onto the player, with Mp3 file manager. I have my albums sortet in folders, and if I drag and drop just a couple of folders to MP3FM, it works fine. But if I, grabs 10< folders i doesn't get past the pre-transfer fase. I have tried to use SonicStage 3.3 but i hangs on 99% transfer. Don't now if it has any connection. And would rather just use MP3FM and GYM. What could be wrong?