Need help. Why does one of my PC's block webpages, but another doesn't

I have the same setup on all my home computers as far as OS and security.

I run Windows 7, 32bit Ultimate. I run MS Security Essentials or whatever you call it.

Anyway I have one PC that flat out REFUSES to open a certain webpage. I get this error:

Unable to connect

Firefox can't establish a connection to the server at servernamehere.net

* The site could be temporarily unavailable or too busy. Try again in a few
moments
* If you are unable to load any pages, check your computer's network
connection.
* If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web.


At first, I thought my ISP might be blocking it because I knew I could browse this page just fine on my HTC EVO 4G Android phone. I tried tethering my phone to this pc for an internet connection, the page STILL refused to load.

I grabbed my laptop which is on the same network, it loads fine.

What would be blocking it from working on one computer but not another on the same network, same internet service provider?

What can I check? I checked in Firefox to see if it was blocked, it's not. I tried IE, didnt help. I tried reinstalling Firefox, nope.

I have no firewall running other then the windows port crap..

Thoughts?

It actually does this with a few pages.

Check your Hosts file, and is there any parental control software in effect on this PC?

No I have nothing on my computer parental control wise.

Also, I only have ONE think in my host file which is a loop back to 127.0.0.1 for something I wanted that has nothing to do with any of these domains.

What web page is it?

It could be blocked by MAC if you've pissed them off. Some sites block by MAC so they don't block all users of an IP address LAN at a University or Starbucks.

However my friend overcame it by clean reinstalling, so it could also be some setting gone awry.

Cough up the apparently embarrassing URL of the site you are trying to reach, please.
It's a must!

I want to make sure you aint clowning us....

Off the top of my head, this could be something in your router even, if it happens to have extreme settings abilities.

I'd be resetting any router and/or cable modem, and retrying also.

Oh it's not anything embarrassing, it's mostly related to hacking Android phones, couple barnyard porn sites, you know, normal internet stuff!

Seriously though, it's mostly Android relates sites but also a couple torrent sites.

That said, I've tried different devices which would have different MAC ID's so thats not the issue. I had already guessed a format would fix it but I didn't want to format yet.

Try resetting your router back to factory defaults.

OK see if this makes any sense, I just tried one of those anonymous web browsing sites, anonymouse.org and the one page that wouldn't load, now loads threw that but not threw direct connection.

BUT like I said, it works on my laptop which is the same isp, same ip address, etc and I tried a couple different MAC ID's from my desktop, the anonymouse.org was the only way it would work.

That said, these pages have NEVER worked from my desktop but do from my laptop so its not like I ever did something to get blocked or banned.

On side note, I didn't think to check anything in the the router, as they work from my laptop, HTC EVO 4G, wife laptop, daughters laptop etc but I guess it can't hurt to try resetting it.