Last week I began experiencing what is known as "flickering pixels" or the "stray pixel issue" in which many pixels the opposite color of its background flash repeatedly across the screen. The phenomenon can be observed here: http://youtube.com/watch?v=Wg33i_tirVM.
This problem is caused by permanent damage to the GPU as a result of overheating. It is widely believed that the Nintendo Wii overheats when the console itself is off while connected to WiiConnect 24. I can attest to this theory as my Nintendo Wii feels quite warm when the console itself is off while connected to WiiConnect 24 although my Nintendo Wii feels normal when the console itself is on. Although playing games are far more intensive tasks than WiiConnect 24, the cooling fan is active during these processes. However, the cooling fan is innactive when the console itself is off while connected to WiiConnect 24 even though heat-producing processes are running.
The problem is a severe engineering flaw and could have easily been avoided. If the Nintendo Wii was capable, with the use of internal temperature sensors, to selectively activate the cooling fan during periods of intense heat when the console itself was off while connected to WiiConnect 24, virtually all cases of overheating could have been prevented. It is irresponsible on Nintendo's part to allow such damaging engineering flaws to be incorporated in their products.
(By the way, I am a huge fan of Nintendo and their games despite what I wrote above. Also, it would be an enormous inconvenience to disable WiiConnect 24 although at the moment it may be the only alternative.)