I started my old VM to configure MOSS 2007 on it and to my surprise, the site www.microsoft.com was not opening. Rest of the websites were opening just fine.
Here is the solution:
Start > Run > (type) “services.msc” (which opens the services mmc) > Now stop the “DNS Client” service. Now open www.microsoft.com in browser and it should open just fine!
Weird enough. :)