環境は
Ubuntu７．１０
Pentium３ ８６６MHz
メモリ：５１２MB
です。

cat /etc/apt/sources.list のリポジトリ一覧は
ーー
# deb cdrom:[Ubuntu 7.10 _Gutsy Gibbon_ Japanese Remix - Release i386 (20071018)]/ gutsy main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

# Line commented out by installer because it failed to verify:
# deb http://jp.archive.ubuntu.com/ubuntu/ gutsy main restricted
# Line commented out by installer because it failed to verify:
# deb-src http://jp.archive.ubuntu.com/ubuntu/ gutsy main restricted

## Major bug fix updates produced after the final release of the
## distribution.
# Line commented out by installer because it failed to verify:
# deb http://jp.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted
# Line commented out by installer because it failed to verify:
# deb-src http://jp.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted

## 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
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
# Line commented out by installer because it failed to verify:
# deb http://jp.archive.ubuntu.com/ubuntu/ gutsy universe
# Line commented out by installer because it failed to verify:
# deb-src http://jp.archive.ubuntu.com/ubuntu/ gutsy universe
# Line commented out by installer because it failed to verify:
# deb http://jp.archive.ubuntu.com/ubuntu/ gutsy-updates universe
# Line commented out by installer because it failed to verify:
# deb-src http://jp.archive.ubuntu.com/ubuntu/ gutsy-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.
# Line commented out by installer because it failed to verify:
# deb http://jp.archive.ubuntu.com/ubuntu/ gutsy multiverse
# Line commented out by installer because it failed to verify:
# deb-src http://jp.archive.ubuntu.com/ubuntu/ gutsy multiverse
# Line commented out by installer because it failed to verify:
# deb http://jp.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse
# Line commented out by installer because it failed to verify:
# deb-src http://jp.archive.ubuntu.com/ubuntu/ gutsy-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/ gutsy-backports main restricted universe multiverse
# deb-src http://jp.archive.ubuntu.com/ubuntu/ gutsy-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 gutsy partner
# deb-src http://archive.canonical.com/ubuntu gutsy partner

# Line commented out by installer because it failed to verify:
# deb http://security.ubuntu.com/ubuntu gutsy-security main restricted
# Line commented out by installer because it failed to verify:
# deb-src http://security.ubuntu.com/ubuntu gutsy-security main restricted
# Line commented out by installer because it failed to verify:
# deb http://security.ubuntu.com/ubuntu gutsy-security universe
# Line commented out by installer because it failed to verify:
# deb-src http://security.ubuntu.com/ubuntu gutsy-security universe
# Line commented out by installer because it failed to verify:
# deb http://security.ubuntu.com/ubuntu gutsy-security multiverse
# Line commented out by installer because it failed to verify:
# deb-src http://security.ubuntu.com/ubuntu gutsy-security multiverse

# Line commented out by installer because it failed to verify:
# Line commented out by installer because it failed to verify:
deb-src http://archive.ubuntulinux.jp/ubuntu-ja gutsy/
# Line commented out by installer because it failed to verify:
# Line commented out by installer because it failed to verify:
deb http://archive.ubuntu.com/ubuntu/ gutsy main restricted multiverse universe
deb-src http://archive.ubuntu.com/ubuntu/ gutsy restricted main multiverse universe #Added by software-properties
deb-src http://archive.ubuntulinux.jp/ubuntu-ja gutsy-ja/
deb http://archive.ubuntulinux.jp/ubuntu-ja gutsy/
deb http://archive.ubuntulinux.jp/ubuntu-ja gutsy-ja/
deb http://archive.ubuntulinux.jp/ubuntu-ja feisty/
deb http://archive.ubuntulinux.jp/ubuntu-ja feisty-ja/
ーー
正直リポジトリを見てもよくわかりません。

sudo apt-get updateを実行したところ
ーー
パッケージリストを読み込んでいます... 完了
W: Duplicate sources.list entry http://archive.ubuntulinux.jp gutsy/ Packages (/var/lib/apt/lists/archive.ubuntulinux.jp_ubuntu-ja_gutsy_Packages)
W: Duplicate sources.list entry http://archive.ubuntulinux.jp gutsy-ja/ Packages (/var/lib/apt/lists/archive.ubuntulinux.jp_ubuntu-ja_gutsy-ja_Packages)
W: これらの問題を解決するためには apt-get update を実行する必要があるかもしれません
ーー
と表示されます。

もう解決したのならアレかもだけど …

一応, 変なトコを指摘しておくです。

deb http://archive.ubuntulinux.jp/ubuntu-ja feisty/
deb http://archive.ubuntulinux.jp/ubuntu-ja feisty-ja/

これは, 「G」の前の「F」の頃の (7.04) ものなので間違いです。
それに gutsy-securityが含まれていないのも問題カモです。