I had no network connection during the installation of XBMC Live, and this is why it was disabled at runtime.
It was not very difficult to fix:
Edited /etc/network/interfaces and added the ethernet interface -- I do not need the wifi (wlan0) and didn't add it.
# Loopback interface auto lo iface lo inet loopback # Ethernet interface auto eth0 iface eth0 inet dhcp
Then restarted the networking service
sudo /etc/init.d/networking restart
A simple ifconfig confirmed that everything went well!