Update Manager funktioniert nicht

Hallo, wenn ich versuche, die CHECK-Taste in "Aktualisiert" zu drücken, wird nicht nach verfügbaren Updates gesucht.

Fehler unterschreiten.

"Failed to Download repository information"

Check your Internet connection..

W:GPG error: http://archive.canonical.com oneiric Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
W:GPG error: http://archive.canonical.com lucid Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
W:Failed to fetch gzip:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_oneiric_main_source_Sources  Hash Sum mismatch
E:Some index files failed to download. They have been ignored, or old ones used instead.

Ubuntu Version 11.10

Versuchen Sie diese in einem Terminal

sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean
sudo apt-get update