Well, maybe the disc sensor needs to be cleaned. I had this same problem with my brawl disc awhile back. if you go to gamestop they should have a lens cleaner for your console.
My wii is giving me error message when I put a disc in it not reading and telling me to ejected and turn it off, is any body know why this happen?
The same thing happened to me awhile ago. You may have to send it to Nintendo to get it repaired