Have you looked at all your lists (not really folders) like Video, Voice, Audiobooks, etc. on the Fuze?
Have you connected to PC in both MSC and MTP modes?
How about right-clicking on the Sansa drive in Windows Explorer (Computer or My Computer) and doing a search by size in each mode?
If you don’t care about what those mystery files are, you could also just use the Fuze’s own Format command (Settings/System Settings, scroll down) and nuke it.
