D-Link DIR-601 :: Cannot Connect To Internet With Vista

This is strange.  I have a client who owns the DIR-601 router.  It connects to a COX cable modem. 

The wireless side works fine.  I can access the internet using wireless connection with no problem. I can connect my Linux laptop both wired and wireless no problem.

However, and this is the puzzle, I cannot connect his Vista computer to the internet.  It worked for a while then just stopped.  From the Network and Sharing screen we can see a good connection to the router, but a big red X from the router to the internet.

I can ping the router with no problems, but I can't ping anything on the net either using a name (www....) or an ip address.

We changed from dhcp to static ip but that didn't work either.  Changed the DNS to the ip address of the COX DNS just in case that was the problem.  Still the same.

I have had COX over to check everything out and everything is fine on their side.

I have Googled all over the place and not found anything that's useful.  I did find one post about a 625 that said to change the WAN speed from auto to 10 or 100, but from what I see the 601 doesn't have this capability.