Have you tried connecting by ethernet cable first?
Have you made sure that you are not using the correct protocol - is ipv6 unchecked, is the pc set to obtain an IP address automatically- see this article.
Have you checked that you do not have a proxy set?
Tools -> Internet Options -> Connections -> LAN Settings -> UNCHECK ALL BOXES HERE
Have you tried renewing your TCP/IP Protocol and Winsock - steps shown in this article if you haven't.