Your Problem:
DNS resolution via local router DNS relay has proven to be a common failure point in my experience.
Try this...
open a terminal.
run this command
Code:
sudo gedit /etc/dhcp3/dhclient.conf
search for this line... #prepend domain-name-servers 127.0.0.1; insert the following line
after that line.
Code:
prepend domain-name-servers 208.67.222.222,208.67.220.220;
Save the file, disconnect and reconnect, then retest.
What this does...
It hardsets your machine to use OpenDNS nameservers.. you may swap 208.67.xxx.xxx with the IP's of your chosen nameservers, although I think you'll find the OpenDNS servers to be much more efficient.
So, no matter what DNS is handed to you by DHCP, your machine will always behave and use just the DNS servers you tell it to.
-Mark Williams