Comment 39 for bug 102675

The /etc/init.d/networking boot scripts hangs because "ifup -a" tries to start many non-existing or not-connected network devices. For many setups/users this script is not necessary at all, since network adapters are managed by network-manager or by detection events. Another workaround is therefore to disable this script:
sudo update-rc.d -n networking remove
(The loopback interface is started by /etc/init.d/loopback)