Comment 15 for bug 514775

There is something easier : install nm-applet. there is an option to re-enable networking :
1- open konsole
2- killall knetworkmanager
3- nm-applet &
4- disown
5- close console

right click on the nm-applet icon an enable networking

if you don't want to enconter this problem uninstall knetworkmanager

I think knetworkmanager is still lacking, we should give it some time before using it daily