Wierd, try reseting your Wii and un-plugging it, that fixes that problem when I got it. However, if this does not work, it is likely that your friends Wii will need a repair. In order to do this, you might want to contact them at 1-800-255-3700 so they can set you up, or contact them Via Webform (sorry, I can't link it to you, darn page is broken). But really, I think your system might just have a problem with the lens not reading how to play the sound on the Wii games.

Hope this helps;

csf103