Can't access certain websites

Hello, I've searched and searched, including this forum, but I can't seem to find the solution.

I cannot access the following websites.
*ithacachildrensgarden.org
*primitivepursuits.com
*huffingtonpost.com (this one I can access, but extremely slow)
*uchicago.edu

I've tried following:
*reset the router and upgraded firmware
*reseated router by plugging off 5 min
*clean-installed my computer (carrying Windows 7)
* reset my DNS using Google Public DNS following instructions on this webpage: http://forums.pcworld.com/index.php?/topic/135911-i-cannot-access-certain-websites/ - this improved browsing speed, but I still cannot access the four sites above.


I have two desktops and 2 laptops. The desktops are connected to a router, and the laptops are using wifi. Laptops are rarely used. All of them have problem accessing the four websites named above.

Thanks for your help.

 

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As all four computers have the same problem it does suggest your router holds the secret, probably in the DNS servers it is using. DNS servers convert a website name to a website number in a form understandable by internet servers.

If you know how to change your DNS servers try setting them to

208.67.222.222 and
208.67.220.220

If that means nothing to you then for just one of your computers tell us which operating system it is using.

 

Hi Earthling, thanks for your response.

I've already tried the public DNS outlined in the steps in the link I posted in the initial post, but other than that I don't know how to change the DNS server. Can you please tell me how to do it (or link to the instruction?)

Our two desktops has Windows 7 (I use 68-bit and my son 34 bit) and my laptops has Windows XP and Windows Vista.

 

Sorry Evie, I missed that link in your first post. If you have already tried the Google servers, which were going to be my next suggestion, it probably isn't a DNS issue. Must confess though that I'm not entirely certain, where there is a difference between the servers set in TCP/IPv4 on your computer (as in the video) and the servers set in your router, which of the two takes precedence. I think it's the TCP/IPv4 that applies but I'm not certain. So in your place I would try resetting the servers in the router, for which you may need the router manual.

It's hard to see what other cause might apply here.