Sounds like they are running some sort of 'nanny' service. They are probably using a proxy server to do so. It may be setup in your firefox and IE settings already (probably why you do not see it when you goto chrome as you just installed it).
If you type in an invalid address (like www.abc.xyz) in the title bar if you land on a either centurylinks web page or the 'squid I cant find your site' page you know you are using a proxy server.
This sort of thing is usually configurable in the web browser. I think Firefox defaults to 'global' settings. Which means use IE's settings. This could have come if you installed any software from your ISP when they first set you up.
You only notice it now because someone borked up the nanny list.
Index 
Flat 
Re: Some sites not loading in FF but will in Chrome
Reply
Re: Some sites not loading in FF but will in Chrome
