Wii Error: 003 occurs after to updating to Wii Menu version 4.2. The update will will check for and automatically remove such unauthorized files. Many Wii owners have come across Error: 003, they have all gotten their Wii from outside the US and now can not use it because the update does not permit the Wii to function.
Beware: There is currently no fix for the error, and leaves you without a working Wii console.