The Disc could not be read.

@johnllovesr try and see if it reads an audio disk as well as different game disk then the one you were trying. Sometimes a disk can cause this error.

It is possible that this is either a dirty laser or a failing laser. First try one of those commercially available CD cleaner kits. Run that a couple of times. If that does not work you could could try to increase the power to your laser. Follow this guide. Just be moderate, you do not want to burn it out. The other thing to try would be a recalibration of the lens. For that follow this guide. After that I'd suggest that you replace either the lens or the optical drive. Nintendo GameCube Optical Laser Lens Replacement Nintendo GameCube Optical Drive Assembly Replacement