Comment 8 for bug 83715

Running 8.04 RC Hardy Heron, experiencing a similar problem. Upgraded a few days ago from 7.10, and in 7.10 I could not print reliably in evince (ended up assuming it was a buggy app and installing acroread instead), and I would get a ~3 minute delay on login. The same annoying ~3 minute delay persisted in 8.04 RC, and furthermore I would often get a gnome session error on login. By good luck I came across this bug (after many unsuccessful attempts to google for similar problem reports). From the comments here, I then tried pinging localhost, and got no answer, and "ifconfig" showed no loopback interface. The solution was very simple - just add these 3 lines to /etc/network/interfaces :
# The loopback network interface
auto lo
iface lo inet loopback

... and I rebooted and now logging in is fast and quick. Yay! I have no idea where the loopback interface lines went to from the interfaces file. Maybe some bit of software deleted it? Maybe I deleted it? Seems a bit unlikely to me though, as I have no recollection of doing that.