Synaptic and update manager will not initialize

I just went and restored all quarantined files in KlamAV and it is running now.
is there a way to effectively scan my puter without causing this?

From the Terminal, perform the following commands below:

sudo -i
rm /var/lib/dpkg/lock
rm /var/cache/apt/archives/lock
dpkg --configure -a

HTH.

sudo cp -arf /var/lib/dpkg /var/lib/dpkg.backup
sudo cp /var/lib/dpkg/status-old /var/lib/dpkg/status
sudo cp /var/lib/dpkg/available-old /var/lib/dpkg/available
sudo rm -rf /var/lib/dpkg/updates/*; sudo rm -rf /var/lib/apt/lists
sudo mkdir /var/lib/apt/lists; sudo mkdir /var/lib/apt/lists/partial
sudo apt-get clean; sudo apt-get autoclean
sudo apt-get update
sudo dpkg --clear-avail; sudo dpkg --configure -a
sudo apt-get install -f
sudo apt-get update
sudo apt-get dist-upgrade

The suggestions for solving both the Update and Synaptic failures in 'natty' do not work.
sudo apt-get update brings a long string of downloads which fail as below. It appears to be a problem with the headers on the repository files.

Ign http://archive.ubuntu.com natty-security/restricted Translation-en_CA
Ign http://archive.ubuntu.com natty-security/restricted Translation-en
Ign http://archive.ubuntu.com natty-security/universe Translation-en_CA
Ign http://archive.ubuntu.com natty-security/universe Translation-en
Fetched 13.7 MB in 41s (327 kB/s)
Reading package lists... Error!
W: GPG error: http://downloadue.info natty InRelease: The following signatures were invalid: NODATA 1 NODATA 2
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/downloadue.info_repo_dists_natty_all_binary-i386_Packages
E: The package lists or status file could not be parsed or opened.

Can you give the output of:

Can you give the output of:

gedit /etc/apt/sources.list

Thanks

Output of: gedit /etc/apt/sources.list

# deb cdrom:[Ubuntu 10.10 _Maverick Meerkat_ - Release i386 (20101007)]/ maverick main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://archive.ubuntu.com/ubuntu natty main restricted
deb-src http://archive.ubuntu.com/ubuntu natty restricted main multiverse universe #Added by software-properties

## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu natty-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu natty-updates restricted main multiverse universe #Added by software-properties

## 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://archive.ubuntu.com/ubuntu natty universe
deb http://archive.ubuntu.com/ubuntu natty-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://archive.ubuntu.com/ubuntu natty multiverse
deb http://archive.ubuntu.com/ubuntu natty-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://ca.archive.ubuntu.com/ubuntu/ maverick-backports main restricted universe multiverse
# deb-src http://ca.archive.ubuntu.com/ubuntu/ maverick-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 natty partner
deb-src http://archive.canonical.com/ubuntu natty partner

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu natty main
deb-src http://extras.ubuntu.com/ubuntu natty main

deb http://archive.ubuntu.com/ubuntu natty-security main restricted
deb-src http://archive.ubuntu.com/ubuntu natty-security restricted main multiverse universe #Added by software-properties
deb http://archive.ubuntu.com/ubuntu natty-security universe
deb http://archive.ubuntu.com/ubuntu natty-security multiverse
deb http://downloadue.info/repo natty all #Ultimate Edition Repository disabled on upgrade to natty
# deb-src http://downloadue.info/repo maverick all #Ultimate Edition Repository

Thanks actionparsnip

You are correct in focussing on the 'sources list'

I removed "Ultimate Edition Repository" from my 'Other sources' list and the problem appears to be solved

Are you using Ultimate?

As I recall I think that I needed it when I was installing Google Earth in Ubuntu 10.10before upgrading to 'natty'

I have used Ubuntu 10.04 but i did not open update manager and synaptic package manager . Please help me.

Google Earth is available in the partner repo as well as a deb on the google website...

What is your issue?