^^^ this is how I got mine working. Use the alt-dol method to watch the video (its like 4 videos in japanese on how to add and remove WM+ addon) and when the wii resets you can turn off the alt-dol and everything should boot fine
cios38 rev13 maybe (i know that compatibility varies from different revs but I think a disc read error is mainly to do with something with the disc itself)
I have the same issue sometimes but I just keep on trying to launch and it will eventually work. It can happen if you use low quality discs or discs other than dvd-r (I myself have used dvd+r and dvd+rw but dvd-r are by far the best.)
It can also be a bad burn which is why they suggest burning...
Man bought a $20 a gauge at Amazon that was all fancy digital went to hook it up did t detect shit, then went back and bought an analog worked right away