Is there any Proxy set or used?
Check to see if set to automatic:
Go Tools/ Options/ Advanced/ click on the Network Tab, then click Settings.
Select the radio button that says Auto Detect Proxy Settings for all this Network
In Internet Explorer,
Go to Tools/ Internet Options/ click on the Connections tab, then click on LAN Settings.
Select Automatically Detect Settings
Click Okay twice.
Try browsing, and if no joy,
Go to the Control Panel then Network Connections.
Click once on your active Connection.
From the menu on the left, select Repair This Connection
Do you get error an message Page Cannot be Displayed
See if there is something in that KB article that helps.