If you’ve got that XP computer at your disposal and can get a connection, you could try reloading the firmware. It’s in one of the top sticky threads. Basically unzip the file and drag fuzeA.bin onto the Fuze root directory.
You could also Format it, which erases all your added content but leaves the system files. Format from its own controls if you can reach them (Settings/System Settings/Format) or through Windows (Format the SANSA FUZE drive to FAT32). Obviously don’t format with Mac or Linux.