What browser are you trying to use to access the Internet? Internet Explorer, Mozilla Firefox, Google Chrome?
You probably have your preference but it might be worth a try to use another one.
This is what I do if I have a problem like that. That way if the other browser works I KNOW that it has the be my old browser messing up and I can 100% direct my efforts to it and not skip all over my computer trying to find the solution.
Sometimes things change (for whatever reason) on browsers on different computers.