Se per il primo punto dovrei aver sistemato il tutto,non e così per il secondo:
totò mi consiglia;
Per il secondo, devi entrare nella cartella lists con i privilegi di amministratore, nel percorso var >lib>apt cancellando le voci che sono doppie
/var/lib/apt/lists/partial
/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_dapper_main_binary-amd64_Packages
/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_dapper_multiverse_binary-amd64_Packages
/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_dapper_Release
/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_dapper_Release.gpg
/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_dapper_restricted_binary-amd64_Packages
/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_dapper_universe_binary-amd64_Packages
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_main_binary-amd64_Packages
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_main_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_multiverse_binary-amd64_Packages
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_multiverse_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_Release
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_Release.gpg
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_restricted_binary-amd64_Packages
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_restricted_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_universe_binary-amd64_Packages
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-backports_universe_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper_main_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper_Release
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper_Release.gpg
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper_restricted_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper_universe_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-updates_main_binary-amd64_Packages
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-updates_main_source_Sources
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-updates_Release
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-updates_Release.gpg
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-updates_restricted_binary-amd64_Packages
/var/lib/apt/lists/it.archive.ubuntu.com_ubuntu_dists_dapper-updates_restricted_source_Sources
/var/lib/apt/lists/janvitus.interfree.it_ubuntu_dists_dapper-upure64_main-amd64_binary-amd64_Packages
/var/lib/apt/lists/janvitus.interfree.it_ubuntu_dists_dapper-upure64_Release
/var/lib/apt/lists/lock
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_main_binary-amd64_Packages
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_main_source_Sources
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_Release
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_Release.gpg
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_restricted_binary-amd64_Packages
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_restricted_source_Sources
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_universe_binary-amd64_Packages
/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_dapper-security_universe_source_Sources
le doppie quali sarebbero

ciao
