If your wii bricks then just download the wii (dolphin) emulator on your pc (if your computer is strong enough to emulate it that is)
^ Ignore this. most computers can't run it at a decent speed, so your better off not breaking your wii
anyway, it probably won't brick your wii, but what I'd do is backup your important stuff (if you can find it) and then format your SD like this
to ensure that all the information is correct.
and if that doesn't do anything, burn your SD card and start warding off whatever evil has befallen your houshold.