When updating your firmware, the default USB communications mode may change.
The Auto Detect mode tries to establish an MTP session, if the computer OS will support it, then it will try MSC mode. For Audible, we need MTP and Windows Media Player 10 or 11.
WiMP supports the transfer of secure media files in the background, as it can access the unique ID and secure clock of the Sansa. Be sure that WiMP 10 or 11 is installed. If you have an XP based machine, for example, the original media player is WiMP 9, which doesn’t support MTP. In the media player, go to Help > Check For Updates and install WiMP 11.
On the Sansa, go to Settings > System Settings > USB Mode > MTP, then plug in.
Let’s see how the Sansa is recognized. If it’s the first time the Sansa is recognized in MTP (Media Transfer Protocol) mode, you’ll see a new “balloon” message at the taskbar announcing the MTP device.
With the Sansa connected, press the [Windows Key] + E to open an Explorer window. If the Sansa is listed under other , at the bottom of the list, it’s seen as a media device. Right click on the Sansa and select properties. You should see a display of the Sansa’s battery status, the firmware version, and the serial number.
In this mode, try opening the Audible Manager, and look in the lower left corner of the client. Does the Sansa list there? If not, at the top of the screen, Help > Check for updates, then select the SanDisk Digital Players plugin.
Return to the lower left, and click on add device. Your Sansa should show up in the list, ready for loading books. Highlight your book file, then click on the Add To Device button.