Ever get stuck with a system where all the various network interfaces don't seem to work or act right?  Wifi just doesn't seem to find any networks, or Ethernet is acting like its a Bluetooth module?  Your system's network settings are probably corrupt, but its an easy fix.

-Navigate to /Library/Preferences/SystemConfiguration/ and remove the preferences.plist file.

-Reboot and you should be good to go.

AuthorMike Muir