To the Original Poster,
Did you happen to recently install a bunch of Windows XP critical updates?
One of them blocked my ability to access some sites using Internet Explorer. I had to go into IE Tools/Options and just guess at the changes I needed to make, but then Internet Explorer allowed me to access those sites again.
Also, ever since installing a bunch of MS critical updates maybe three weeks ago, I can no longer download anything to my desktop, or send any shortcuts to my desktop. There were too many (eleven on one day!) to try to keep uninstalling and rebooting, and experimenting to try to download a file to the desktop, so I gave up. Thanks, Microsoft.
(I get a message that download to desktop completed, but it is nowhere to be seen and no, there are no other users, no other desktops it could have gone to.)
So, if you installed any critical updates from Microsoft very recently, also, that could be the problem with not being able to access particular websites.
Gail