I had this problem just this morning as well. Also a D-Link router. I changed my DNS settings to that 4.2.2.1, and 4.2.2.2, and it started working again, thanks!
For those having problems, just follow this tutorial:
http://portforward.com/networking/staticip.htm
Then when you get to the: "Use the following DNS server addresses", use
Preferred DNS server: 4.2.2.1
Alternate DNS server: 4.2.2.2
Or any other set of DNS servers that may work for you. (Those worked for me).