Hey, im also having this problem with my wii =/
Green pixels would appear every now and then when i play zelda, usually appears during sunset, or near water.
I tested on 2 different TVs and the problem still occurs. When i switch to the composite cables, i still notice the green pixels. They dont stand out as much compared to the component cables since everything is so blurry in zelda.
I will try calling the technical support to see if the warranty can cover this issue.