The Sansa Fuze information support is on next site:
Sansa Fuze can connect in either MTP or MSC mode.
MTP is Media Transfer Protocol when a software program like Windows
Media Player 10 or higher is installed.
MSC is Mass Storage Class when the player is detected as an external flash drive in "My Computer".
The connection mode can be set to one of the following USB modes:
the player will connect in MTP or MSC mode. It depends on the drivers that are installed for the USB ports for the operating system and extra media software, if the data on the player can be detected. In auto detect
mode, MTP mode detection is only possible when having Windows Media Player 10 or higher installed.
detection on operating system Windows XP SP2 or higher, in Windows Media Player 10 or higher.
detection on operating system Windows in the explorer in "My Computer" and on MAC operating system.
Look in the manual on page 35 = page 38 in the pdf file, how to switch the USB mode under System Settings in the player