C'est l'erreur suivante:
W: Failed to fetch http://ppa.launchpad.net/sun-java-community-team/sun-java6/ubuntu/dists/quantal/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/sun-java-community-team/sun-java6/ubuntu/dists/quantal/main/binary-amd64/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
sudo apt-get clean