"Waiting for network configuration" upon boot

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http://unix.stackexchange.com – When I boot, I get the error message waiting for network configuration, then waiting an additional 60 seconds for network configuration. I had edited /etc/network/interfaces file before the above message, so as to surf through a friend's laptop using Ethernet cable; then, after restoring the file, I still get the same message. I have searched in the internet but I didn't find anything helpful. The content of /etc/network/interfaces is: auto lo iface lo inet loopback What is wrong? (HowTos)