WinXP PRO, latest updates

For an unexplained reason a friend of mine is unable to connect to some Web
pages,
e.g. http://www.flyzoom.com/ No specific error message, but "The page
cannot be displayed..."
Deleted Cookies and Files, rebooted several times, ran SpyBot, Ad-Aware,
checked restricted sites.
What else can we do to fix the Browser or whatever problem he has. He does
not have an alternate browser installed.
Thank you

Otto