Overheating sounds like a possible cause for this type of corruption. But in my case it would have to have been the heat that made a permanent fault. It happens even if the unit has been unplugged for some time.

I finished Zelda with 96 hours of play in 2 weeks, so it's strange it didn't overheat then. But I suppose at that time it's also protected by a fan...

I've heard good things about Nintendo customer support. I suppose I'm going to have to find out about this for myself. I'm just sorry I'll lose my Wii code and have to re-add everyone.

Bruno