Parece haber problemas con los repositorios de Ubuntu, tanto en España como internacional

http://archive.ubuntu.com/ubuntu/dists/disco/Release
404 Not Found [IP: 91.189.88.142 80]

http://archive.ubuntu.com/ubuntu/dists/disco-updates/Release
404 Not Found [IP: 91.189.88.142 80]

http://archive.ubuntu.com/ubuntu/dists/disco-security/Release
404 Not Found [IP: 91.189.88.142 80]

http://archive.ubuntu.com/ubuntu/dists/disco-backports/Release
404 Not Found [IP: 91.189.88.142 80]