Comment 8 for bug 416991

First I used a sources.list file from another installation of the same version ubuntu.

This did not resolve my issue.

Second I found I did not have a /etc/apt/apt.conf file

So I created a file by going to terminal and typeing.
sudo gedit /etc/apt/apt.conf
and add this line:

APT::Cache-Limit 20971520;

I went with a big size just to make sure size wasn't an issue.

I just installed SVN so I know everything is working.

Thanks for what little you did share, it forced me to look a little deeper at my issue.