Not sure exactly when but I did an upgrade to KDE4 and the kernel and in the process my networking stopped working, wireless and wired. It worked fine in recovery mode and I did another update in case there was a fix but no dice.
Fortunately I have a friend who knows the score, he told me to:
sudo nano /etc/NetworkManager/nm-system-settings.conf

and set managed=true instead of false. I then had to:
sudo nano /var/lib/NetworkManager/NetworkManager.state

and set NetworkingEnabled=true. I then had to restart the service:
sudo service network-manager restart

and it was all good again. Well done whoever made that happen in a package upgrade! Most people, including me, would not easily find out what has happened and would conclude that Windows works better even if we hate M$.