If the firmware isn't fully updated, try doing that to see if it makes a difference.
Ok, I had an old that wasent reading all my disks, so I currently have a new that was given to me from a friend. In the old Wii my USB was working perfectly fine, so I put all my saved files into it to transfer it to the new one....
The new Wii is says "the device inserted in the sd card slot cannot be used".
Thank you in advance.
YAHOOOOOO it WORKS!!!!!!!