Explorer Cannot display page

On a post 360 install on another computer I can't go to any website that requires a sign in such as Facebook, Yahoo. Mail, etc.  I reset the firewall, went to program control and "allowed" internet explorer, What else can I do?

On a post 360 install on another computer I can't go to any website that requires a sign in such as Facebook, Yahoo. Mail, etc.  I reset the firewall, went to program control and "allowed" internet explorer, What else can I do?