I had the same experience. I found a solution to my problem that may work for others: In my router I have a setting to toggle filtering of WAN proxy requests. (Linksys WRTP54G - Vonage) Filtering the WAN proxy requests (disabling these requests) prevents apt from finishing during installation. When I unchecked this filter and reinstalled, the install proceeded without incident.
I also had success finishing installation when I disconnected my PC completely from my network during install. Installation finished but apt would not work. It was only when I unchecked this feature in my router that I could finish install and use apt to get security updates, etc. -- Install hangs when "setting up primary installation repository" https://launchpad.net/bugs/25522 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
