In ,
ConfusedJ had this to say:

Looking for guidance here as I accept this may not be an IE issue. I
have a home network connecting through a DLink router to ADSL. All
worked fne until today (and no known changes made). Now I cannot
access any part of the BA website (www.britishairways.com or
www.ba.com) as I get the "page unavailable" screen. BUT - the
website is working as I can access through a dial up via a
non-networked laptop and I get the same error on all PCs on the
network. All other websites that I try are fine so I am trying to
think of a (probably) router error that would effectively block just
one site..!! I have rebooted the router. I shall of course seek
guidance on a Dlink forum but hoped someone here might also be able
to help

It could be blocked any number of ways, I was able to access the site here.
Perhaps you've got it blocked with a firewall? It's in your hosts file with
the 127.0.0.1 IP address. You could have used some "acceleration software"
that caches IP addresses for sites and the numeric address has changed. It
could have been temporarily unavailable at that time and you can try later?
You could just need to delete your temporary internet files for instance but
that's probably not it. You could try it and see. Without more information
I'm not really sure what to tell you but it could be any one of those, or
more, things.

Galen
--

"My mind rebels at stagnation. Give me problems, give me work, give me
the most abstruse cryptogram or the most intricate analysis, and I am
in my own proper atmosphere. I can dispense then with artificial
stimulants. But I abhor the dull routine of existence. I crave for
mental exaltation." -- Sherlock Holmes