NeoGamma and the Disc Channel both use different IOSes. If you get a game to work in NeoGamma, it doesn't mean it will also work through the Disc Channel.
To block disc updates, see THIS.
To update IOSes used through the Disc Channel, see THIS.
By the way, why are all your games NTSC, and not PAL? My guess is that you live somewhere in America, and that you have a PAL Wii?