It's probably a dns problem
I can test it later, I know someone with earthlink. For now just edit /etc/resolv.conf and remove everything from it.
this will do the trick..
echo > /etc/resolv.conf
then connect and see if nameservers get added to the file and that it works.
If it still does not work then maybe it's your firewall settings. Modify your firewall or try it momentarily with no firewall.