Has been wiing for a week. I was not playing any Wii game, but installing Homebrew Channel, USB Loader GX. I can now place all my games into a portable hard drive. This got rid of the intermittent DVD reading problem.
In the process, the System Menu has been updated to version 4.2U.
And, I have installed FCE Ultra GX to play the nostalgic Nintendo games, such as Bomberman, Battle City and so on.