What could be wrong with my game "MarioKart" for GameCube ?

Yeah, that is what I was thinking too

I have Mario Kart for Gamecube for over a year and it still works for me…

it sounds like the disk is dirty or scratched. Try using a disk cleaning system. If the disk is scratched a cleaner may not be able to cure the fault, but it is often possible to “repair” the scratch by rubbing it with toothpaste, then cleaning off all the residue …..

….. however, I would only recommend doing that as a last resort.

I’m kind of scared to use toothpaste, I seen someone do that to a disk…and it came out more scratched than before! :/

Yes that is why I said “… I would only recommend doing that as a last resort …”.

However I know several people who have done this successfully ( including myself ! ).

Take a look at this link: http://funadvice.com/r/14oisuk2huq

That link warning about the dangers, and now this:

http://funadvice.com/r/14oit677q3d

explaining how it can be done despite the dangers. I assure you I have restored full functionality of disks with the toothpaste trick (having exhausted all other possibilities first ! )

Thank you so much! :] I used your links, and I cleaned the disk with toothpaste. It worked! :D