NSMB disc swap?
After burning 7 dvd+rs from different images, patches etc. I gave up on this game. I always got the disc read error. Well a couple hours after ejecting disc #7 I came back to find the wii on and "Insert NSMB disc..." on the screen. I tried one last time and it worked! I haven't been able to recreate the circumstances exactly yet, but I did successfully boot it from a single dvd+r.
Invest in some verbatim dvd-r dvds. They are the most compatible. It sounds like a media error since it worked once.
Seconded, you are wasting your time and money with +r discs. Even if the +r discs do work the Wii drive will grind itself into an early grave trying to read them.