Unplug the gamecube controller until it completely loads.
I rarely use bootmii, but after I downloaded the wii sistem menu black theme, it just won't load! I select the "load bootmii" button in the homebrew channel. I can see the menu image flashes, but them the wii reset! if the problem is with my wii menu theme, is there anyway to uninstall? I want to make a NAND backup to play WADs via ISO.
Do you have bootmii folder on the SD or USB? I know I've removed mine.
You have to have the bootmii folder on your SD. If you don't have a backup you can use the Hackmii installer to create a new one.
No other gamecube hardware plugged in, memory cards?
Have you gotten bootmi to load before using that sd card?
Do a full format on your SD card and try again. You can also try to change the boot delay in the bootmii.ini file.
In your bootmii folder you will find a file called bootmii.ini. Open it with notepad or wordpad and edit the line with "BOOTDELAY=x" were x = seconds. If you have a # in front of BOOTDELAY=x make sure you delete it.