I've had a recurring problem with my Wii for about 6 months now.
I click the disc channel and about 1 time out of 3 the screen will go black and the controller will disconnect. The only way to turn it off is to hold down the power button or disconnect it from the wall.
Some of you will say things such as:
"silly frumage, its because u modded ur wii lol "
But this was happening WAY before I even opened my Wii up.