The exact same issue that happened to Japanese gamers that bought Brawl is now happening with Mario Kart Wii. Some people that purchased the game are complaining that their Wii cannot read the disc, and the game is freezing/crashing. Nintendo has once again stated that the problem is due to Mario Kart Wii being a double-layer disc. Nintendo will clean your Wii for you, which should do away with the problem. I would be very interested to find out if the people experiencing the Mario Kart Wii problem also purchased Brawl.

Link