accessing microsoft websites, please help!

Hi, i recently reinstalled the operating system that came with my dell 8400. It is windows media center 2005, and is a liscensed copy. I connected to the intetnet and everything seemed to work. I cant get to windows update, the page wont load. I also discovered i cant get to mozilla, microsoft, or xbox. These sites resolve ip address when i ping them, but the page wont load. When i try to get to non microsoft websites, like xbox-scene, it has the same error. Everything else on the internet is working fine. MSN messenger and hotmail also do not work.  I have ran spyware tools like spyware doctor, avg, registry mechanic and others. the host file is fine and there are no virus on a scan. This has me stumped.

 

can anyone help me?

 

thanks

 

mike hinnenkamp