Erro na instalação e update dos app (soh funciona os de fabrica)

[lyricthrone]

Esse erro aparece sempre que eu tento instalar um programa novo ou atualizar algum programa =/ alguem pode me ajudar?

Fetched 1,576 B in 14s (111 B/s)                                               
Reading package lists... Error!
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://security.ubuntu.com precise-security Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>

W: GPG error: http://planet76.com ./ Release: The following signatures were invalid: BADSIG 176A5C84ED67C9ED System76 Development (System76 Development Package Signing Key) <dev@system76.com>
W: GPG error: http://archive.canonical.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
W: GPG error: http://ppa.launchpad.net precise Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY EFD5FA852F20733F
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://extras.ubuntu.com precise Release: The following signatures were invalid: BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <ftpmaster@ubuntu.com>

W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us.archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>

W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us.archive.ubuntu.com precise-updates Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>

W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us.archive.ubuntu.com precise-backports Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/precise-security/Release 

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/Release 

W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/Release 

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/Release 

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/Release 

W: Some index files failed to download. They have been ignored, or old ones used instead.
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_precise-updates_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.