Yesterday in my country was holiday, so I turned on my Wii to play and BOOM, I got a black screen saying "system error - repairing"
NOOOOOOOOOOOOO!!!!! WHY??? NOOOOOOO!!!! 
I go into panic for a dozen of minutes: I accidentally removed BootMii with the latest Homebrew Channel update and I can't enter into recovery mode, then, searching on the net (I was about to buy a SaveMii...), I discovered that it was an april's fool joke of the Preloader (now called Priiloader, this joke has been removed)
Yay!, What fun... 
After that I remembered that someone in 2009 had the same problem...