Software :: Cannot Install/uninstall Programs Because "package System Is Broken"

I am running Ubuntu 10.04 In Ubuntu Software Center I tried to remove Document Viewer. I then tried to install PDF Editor Neither worked and I got the below message The Package system is broken Check if you are using third party repositories. If so disable them, since they are a common source of problems. Furthermore run the following command in a Terminal: apt-get install -f� I tried to run apt-get install -f and got this message

david@leibnitz:~$ apt-get install -f
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
david@leibnitz:~$

I switched to root and got this

david@leibnitz:~$ apt-get install -f
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
david@leibnitz:~$ root

[code].....

At some point while trying install/uninstall I got a message that said to check the broken filter to see which file is broken. At present, I cannot install/uninstall programs. I do not know how to access the broken filter. And I cannot run apt-get install -f