Problems connecting to various websites

Reciently I have no been able to access websites in safari such as firefox.com or myspace.com. This is very strange. It is fine on many of webpages. But I've looked at all the settings for safari and general os x settings. And I know its not my network because my friend has a new MacBook Pro and he can view the websites on his computer from the same network. Also I cannot view these websites from his home network. I have tried pinging the destination which results in the error message no route to host. Anyone have any ideas?