Instructions
Ensure that you inserted the disc correctly. If your Wii console is laying flat, the disc goes in label side up. If it is upright, the label side of the disc loads on the right.
Check that the last game was ejected properly. Ejecting a disc in the middle of play can cause the error. Always exit a game and return to the Wii menu before ejecting the disc.
Clean the disc. Make sure the disc is free of dust and debris if you have problems with the same game disc repeatedly.