Windows 7 blocking web site access

I recently purchased a clone system running Windows 7 Pro 64-bit and have found that all browsers are blocking web sites on the system . Originally, the message said "Site not found" even though I can easliy access them all from my XP Pro machine. I even have a problem logging into a member site with the same credentials that work on my XP Pro system. I have tried, IE 9, Firefox, Minefield, Safari and Chrome with the same results though now I am getting a message page that mentions IIS 7.5 and shows a 404.0 error code. I have turned off Windows Firewall and the problem occurred before I loaded any AV software. HELP!!!

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