This is rather easy to do and follows the general method used in many Creative players. First- copy all your data to a computer hard drive.
1. Detach the ZEN Vision W from the PC and ensure that the player is turned off.
2. Remove the battery.
3. Move and hold the Power button to the Power On position and
4. Re-insert the battery into the ZEN Vision W.
5. Hold the Power button until the Recovery Mode appears.
The following options will be displayed:
Clean Up: Scans the player and removes invalid links from its music library. Does not affect music files themselves.
Format (All) which erases all content
Reload OS/ Firmware which erases your player's firmware.
Reboot: Reboots the device.
The Format command will essentially defrag the device. The reload the data.
I don't know that you can mount the device as drive, but you might not need to. If you go to the recovery mode, they have a clean up option built into the firmware. For the Vision W, simply take the battery out, push and hold the power button over and insert the battery back in. Hold the power button over until the recovery mode appears. Then select clean up.
The same is true of all the Creative players and you can find how to get the recovery modes at this link : http://us.creative.com/support/kb and put in SID4794 for the keyword.
Hope this helps.
Greg from Portland