Domain Name Server Configuration Problem.

I just got a laptop a month ago– a brand new Samsung with Windows 7 installed on it. The wireless feature is built right in. I use a rather unreliable router with a reliable ISP and everything works fine. This morning my internet worked fine but about an hour after I used it wouldn't connect. When I clicked on Diagnose and Repair, I got this message:
There may be a problem with your Domain Name Server (DNS) configuration.
Windows failed to find the well known host "www.microsoft.com" using DNS. The server may be down.
The internet works absolutely fine for both of my roommates, and even when I plugged my laptop directly into the modem I got the same problem.
Please, help on this.
