man im a big noob. but i might be able to help.. iv read that all the problem lies in power right ? i have this cable. on one end it connets to the harddisk or any other mini usb device, one end it connets to the computer (in this case aur n900) and the other to a wall charger ! check the picture. if u cant see it, let me know give me ur emale. i will send u.
hope this helps man.