If you are getting the specific message, "An error has occurred. Turn the Power Off and check the Nintendo GameCube Instruction Booklet for further instructions." This means there may be an internal problem with the system.
Check Individual Game Disc problems or Multiple Game Disc problems (depending upon how many games exhibit the problem) to see if the cause of the message is a dirty or damaged disc.
If the disc appears fine or works properly in another system, please click here for more information.