JD and I both bought Sansa Fuze 4GB MP3 Players from Woot.

Mine worked fine, but his was acting very flakey.  It refused to see any music in sub-folders.  If you copied music into the root of the Music share it would see the songs, but it would freeze as soon as it started playing. Both devices successfully had taken the update to the latest firmware.

I had changed the USB settings on my device to ‘MSC’ mode, to prevent ubuntu from thinking it was a camera and allowed me to work with the files in a more pleasant view.  In this ‘MSC’ view I saw 5 files in the root of the device including 4 .sys files and a .sdk file.

Just on a wild hunch i copied the .sys files from the working device, to the flakey device and this corrected all issues. Both are now working great, playing all music files and properly seeing sub-folders.