Linux MintにcURLをインストールできない

インストールしようとしています。カールインストールできるようにルビーバージョンマネージャ。

私はこう書く:

sudo apt-get update && apt-get install curl

次の出力を取得します。

E: Some index files failed to download. They have been ignored, or old ones used instead.
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

それから私はこう書く:

sudo rm /var/lib/apt/lists/lock

sudo rm /var/cache/apt/archives/lock

その後、cURLを繰り返しインストールし、以下を取得しました。

E: Some index files failed to download. They have been ignored, or old ones used instead.
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

修正する:

出力は次のとおりです

 $ sudo apt-get install curl
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  curl
0 upgraded, 1 newly installed, 0 to remove and 13 not upgraded.
Need to get 179 kB of archives.
After this operation, 373 kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  curl
Install these packages without verification [y/N]? y
Err http://archive.ubuntu.com/ubuntu/ natty-updates/main curl i386 7.21.3-1ubuntu1.2
  404  Not Found [IP: 91.189.91.14 80]
Err http://security.ubuntu.com/ubuntu/ natty-security/main curl i386 7.21.3-1ubuntu1.2
  404  Not Found [IP: 91.189.88.149 80]
Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/c/curl/curl_7.21.3-1ubuntu1.2_i386.deb  404  Not Found [IP: 91.189.88.149 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

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アップデート2：

使っていますLinux Mint11（Rosinka）、インターネットに接続されています。