nella directory /var/lib/apt/lists c'era

lock
mi.mirror.garr.it_mirrors_debian_dists_squeeze_mai n_binary-i386_Packages
mi.mirror.garr.it_mirrors_debian_dists_squeeze_mai n_source_Sources
mi.mirror.garr.it_mirrors_debian_dists_squeeze_Rel ease
mi.mirror.garr.it_mirrors_debian_dists_squeeze_Rel ease.gpg
mi.mirror.garr.it_mirrors_debian_dists_squeeze-updates_main_binary-i386_Packages
mi.mirror.garr.it_mirrors_debian_dists_squeeze-updates_main_binary-i386_Packages.IndexDiff
mi.mirror.garr.it_mirrors_debian_dists_squeeze-updates_main_source_Sources
mi.mirror.garr.it_mirrors_debian_dists_squeeze-updates_main_source_Sources.IndexDiff
mi.mirror.garr.it_mirrors_debian_dists_squeeze-updates_Release
partial
security.debian.org_dists_squeeze_updates_main_bin ary-i386_Packages
security.debian.org_dists_squeeze_updates_main_sou rce_Sources
security.debian.org_dists_squeeze_updates_Release
con
codice:
sudo rm /var/lib/apt/lists/* -vf
è stato rimosso tutto meno la directory "partial"

ora con apt-get update ottengo:
Scaricamento di:1 http://security.debian.org squeeze/updates Release.gpg [836 B]
Ign http://security.debian.org/ squeeze/updates/main Translation-en
Scaricamento di:2 http://mi.mirror.garr.it squeeze Release.gpg [1672 B]
Ign http://security.debian.org/ squeeze/updates/main Translation-it
Scaricamento di:3 http://mi.mirror.garr.it squeeze Release.gpg [1672 B]
Ign http://security.debian.org squeeze/updates Release
Scaricamento di:4 http://mi.mirror.garr.it squeeze Release.gpg [1672 B]
Scaricamento di:5 http://mi.mirror.garr.it squeeze Release.gpg [1672 B]
33% [5 Release.gpg 0 B/1672 B 0%] [In attesa degli header]
e continua così...