Q:

Untrusted Package Errors, After installing Security Tools

I installed all of security tools provided from the ubuntu.com and some others listed in other websites. Then i added backtrack repositories to update them. And used update manager to update the tools. Since then, I am getting Untrusted Package errors every time, every where, whether is update manager or software center. Unless I do it from the terminal.
I read in few posts, that they are caused by keys, not being authenticated properly so i needed to update them. I tried that too, but none of them are working.
Help me fix this issue.
I have tried solution suggested in this question. It didn't change anything
 sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 40976EAF437D05B5
Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.tSQJ1K1D2g --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyserver keyserver.ubuntu.com --recv-keys 40976EAF437D05B5
gpg: requesting key 437D05B5 from hkp server keyserver.ubuntu.com
gpg: key 437D05B5: "Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1

A:

I have solved this problem following steps up from here.
First I removed all extra software source and then I ran these commands one by one.
sudo fuser -vvv /var/lib/dpkg/lock  
cat /etc/lsb-release
uname -a
sudo rm /var/lib/apt/lists/lock 
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 rm /var/cache/apt/*.bin
sudo mkdir /var/lib/apt/lists
sudo mkdir /var/lib/apt/lists/partial
LANG=C;sudo apt-get clean
LANG=C;sudo apt-get autoclean
LANG=C;sudo apt-get --purge autoremove
LANG=C;sudo apt-get update -o APT::Cache-Limit=25165824
sudo dpkg --configure -a
sudo dpkg --clear-avail
LANG=C;sudo apt-get -f install
LANG=C;sudo apt-get --fix-missing install
LANG=C;sudo apt-get update -o APT::Cache-Limit=25165824 && sudo apt-get dist-upgrade

