こんにちは。
アップデートマネージャを起動し、いくつかアップデートされる項目があったので、「アップデートをインストール」をクリックし、インストールを開始しようとしたのですが、
以下のようなエラーメッセージが出てきて、パッケージのダウンロードに失敗します。

W: http://ubuntu.mithril-linux.org/archives/pool/main/c/coreutils/coreutils_7.4-2ubuntu3_i386.deb の取得に失敗
  ubuntu.mithril-linux.org:80 (211.10.155.48) へ接続できませんでした。 - connect (110: Connection timed out)


W: http://ubuntu.mithril-linux.org/archives/pool/main/t/tar/tar_1.22-2ubuntu1_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/c/coreutils/mktemp_7.4-2ubuntu3_all.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/o/openssl/libssl0.9.8_0.9.8k-7ubuntu8.2_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/o/openssl/openssl_0.9.8k-7ubuntu8.2_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/k/krb5/libk5crypto3_1.8.1+dfsg-2ubuntu0.3_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/k/krb5/libgssapi-krb5-2_1.8.1+dfsg-2ubuntu0.3_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/k/krb5/libkrb5-3_1.8.1+dfsg-2ubuntu0.3_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/k/krb5/libkrb5support0_1.8.1+dfsg-2ubuntu0.3_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/c/couchdb-glib/libcouchdb-glib-1.0-2_0.6.3-0ubuntu2_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/c/couchdb-glib/libdesktopcouch-glib-1.0-2_0.6.3-0ubuntu2_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/p/python-imaging/python-imaging_1.1.7-1ubuntu0.1_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:


W: http://ubuntu.mithril-linux.org/archives/pool/main/s/screen/screen_4.0.3-14ubuntu1.2_i386.deb の取得に失敗
  Unable to connect to ubuntu.mithril-linux.org:http:

因みに、sources.listの中身はこんな感じでした。

# deb cdrom:[Ubuntu 10.04 LTS _Lucid Lynx_ - Release i386 (20100429)]/ lucid main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

# deb cdrom:[Xubuntu 10.04 _Lucid Lynx_ - Release i386 (20100429)]/ lucid main multiverse restricted universe
deb http://ubuntu.mithril-linux.org/archives/ lucid main restricted
deb-src http://ubuntu.mithril-linux.org/archives/ lucid main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://ubuntu.mithril-linux.org/archives/ lucid-updates main restricted
deb-src http://ubuntu.mithril-linux.org/archives/ lucid-updates main restricted

## 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 http://ubuntu.mithril-linux.org/archives/ lucid universe
deb-src http://ubuntu.mithril-linux.org/archives/ lucid universe
deb http://ubuntu.mithril-linux.org/archives/ lucid-updates universe
deb-src http://ubuntu.mithril-linux.org/archives/ lucid-updates 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 http://ubuntu.mithril-linux.org/archives/ lucid multiverse
deb-src http://ubuntu.mithril-linux.org/archives/ lucid multiverse
deb http://ubuntu.mithril-linux.org/archives/ lucid-updates multiverse
deb-src http://ubuntu.mithril-linux.org/archives/ lucid-updates multiverse

## Uncomment the following two lines to add software from the 'backports'
## repository.
## 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.
# deb http://jp.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse
# deb-src http://jp.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse

## 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 http://archive.canonical.com/ubuntu lucid partner
# deb-src http://archive.canonical.com/ubuntu lucid partner

deb http://ubuntu.mithril-linux.org/archives/ lucid-security main restricted
deb-src http://ubuntu.mithril-linux.org/archives/ lucid-security main restricted
deb http://ubuntu.mithril-linux.org/archives/ lucid-security universe
deb-src http://ubuntu.mithril-linux.org/archives/ lucid-security universe
deb http://ubuntu.mithril-linux.org/archives/ lucid-security multiverse
deb-src http://ubuntu.mithril-linux.org/archives/ lucid-security multiverse
どうすればよいのか、ご教示お願いします。