1. Check to see if there is nothing interfering with your AC adapter and that the AC adapter and air vents are clean and free of dust.
2. Check to see if the game cube disk is free of dust and scratches.
3. Is there a wii speck mic. or anything that the game does not require connected to the wii? If so, try unplugging anything the gamecube game does not require.
4. You can buy a LED scanner cleaner online or at a near by gaming store which helps clean the inside of the wii to help it scan disks better.
5. contact Nintendo about the dilemma.
Hope any of this info helps!