I had exactly the same problem but have sorted it.
Its to do with a the setting in the player.
Go into the system menu:-
Highlight "Online Device" press "M"
Highlight "USB Disk" press "M"
Exit from settings menu and connect to the PC, this makes the thing work like a standard USB drive. The other mode is for syncing to a media player like Windows Media Player.
Hope this helps
Earthshine
October 2007