no idea whether this is news to anyone, but it sure was to me when I discovered it last night.

Mario Kart Wii backups have one screwed up /not functioning GP. as far as I know there was no way to get around that prob. I recently switched my backup system to load exclusively from USB and I tried that GP that wasn't working on Mario Kart and voila - all of a sudden it is working.

Now that I am loading all my games from USB my downloaded Mario Kart backup is fully functioning. just thought I'd share.