Comment 5 for bug 203593

I had this same problem after upgrading Kubuntu 7.10 to 8.04 LTS (only minutes ago...)
In my /etc/hosts it was
127.0.1.1 franz-laptop-new instead of
127.0.1.1 laptop-new

I could not find any other solution but to boot in recovery mode and start as root, then edit /etc/hosts file.
No way to become root otherwise.

This is really a nasty bug, specially for non experienced users! I reccomend giving it high priority.