Comment 3 for bug 110616

I was experiencing the very same problem and I must admit I think it's avahi to blame.

I tried stopping network manager (including the daemon) and various services and all my session's startup software, with no success. I got a quick desktop/login only if i disabled all my network interfaces but loopback.

As soon as I disable avahi, all the problems solved and my hosts, resolv.conf and network/interfaces just stayed the same. I don't use static IPs and my PC is still in the same network, the error appeared after an upgrade.