Problema de atualização

Problema de atualização

Deixe-me agradecer antecipadamente por ler e tentar me ajudar. Obrigado! Desculpe pela edição terrível também tive que alterar alguns dos links porque não sou respeitável :)

Meu problema é o seguinte: Ao abrir o Update software center, aparece uma janela de erro dizendo: "Os itens não podem ser instalados ou excluídos até que o catálogo de pacotes seja reparado ..." Clico em reparar, mas ele falha.

executar sudo apt-get update falha, este é o relatório de erro:

"W: Failed to fetch archive.ubuntu.com/ubuntu/dists/precise/Release  Unable to find expected entry 'restricted/source/Sources' in Release file (Wrong sources.list entry or malformed file)

W: Failed to fetch bzip2:/var/lib/apt/lists/partial/us.archive.ubuntu.com_ubuntu_dists_precise-updates_main_binary-i386_Packages  Hash Sum mismatch

E: Some index files failed to download. They have been ignored, or old ones used instead."

Conteúdo de source.list:

# deb cdrom:[Lubuntu 12.04 _Precise Pangolin_ - Release i386 (20120423)]/ precise main multiverse restricted universe

# See help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb us.archive.ubuntu.com/ubuntu/ precise main restricted
deb-src us.archive.ubuntu.com/ubuntu/ precise main restricted

## Major bug fix updates produced after the final release of the
## distribution.

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb us.archive.ubuntu.com/ubuntu/ precise universe
deb-src us.archive.ubuntu.com/ubuntu/ precise universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb us.archive.ubuntu.com/ubuntu/ precise multiverse
deb-src us.archive.ubuntu.com/ubuntu/ precise multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.


## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb archive.canonical.com/ubuntu precise partner
# deb-src archive.canonical.com/ubuntu precise partner

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb extras.ubuntu.com/ubuntu precise main
deb us.archive.ubuntu.com/ubuntu/ precise-updates restricted main multiverse universe
deb-src extras.ubuntu.com/ubuntu precise main"

Eu tentei: lendo outras respostas do tipo e fazendo o que eles sugeriram:

1. mudando o servidor que uso

2.

    sudo apt-get autoclean
    sudo apt-get autoremove
    sudo apt-get -f install

3. o seguinte também não funcionou:

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

Ajude-me askubuntu, você é minha única esperança! obrigado novamente

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