I read some where on here about this problem, but I can't find it. Anyhow, my system is doing the same thing. The game is in black and white with small lines gong through. When we play any other game, everything is fine.
You are more than likely planning an out of region game. Set your loader to force whatever region your on (NTSC, PAL)
Why does everyone assume they are the only person in the world to have this issue?
This question is asked at least once a day, every day since Wiihacks began.
The forum search box would have helped, just type in Black and White and be astounded how many threads ask the same question.
Not really doing much Wii stuff these days.