questo è il mio file sources.list
codice:
# Ubuntu supported packages
# GPG key: 437D05B5
deb http://it.archive.ubuntu.com/ubuntu dapper main restricted
deb http://it.archive.ubuntu.com/ubuntu dapper-updates main restricted
deb http://security.ubuntu.com/ubuntu dapper-security main restricted

# Ubuntu community supported packages
# GPG key: 437D05B5
deb http://it.archive.ubuntu.com/ubuntu dapper universe multiverse
deb http://it.archive.ubuntu.com/ubuntu dapper-updates universe multiverse
deb http://security.ubuntu.com/ubuntu dapper-security universe multiverse

# Ubuntu backports project
# GPG key: 437D05B5
deb http://it.archive.ubuntu.com/ubuntu dapper-backports main restricted universe multiverse
e l'update dei repository l'ho già fatto.