It is either due to an overused lens, whether it be dirty or scratched, or you may not have the latest Wii update. That is what I have heard plagues the Wii version. I'd recommend checking if there are any new updates to download before dropping $75 without need.
"Nothing is impossible, Mario. Improbable, unlikely, but never impossible."
- John Leguizamo as Luigi in the Super Mario Brothers Movie