See what happens in the [https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Firefox SafeMode].

It's complicated. There are a lot of links in the chain... Do you want to check whether Firefox is actually sending a request to Facebook's numerous different servers and receiving a normal response? Here's how you can try that. While viewing the HuffPost (or other) page, press Ctrl+Shift+k to open the Web Console in the lower part of the tab. Along its top edge, click Network. Then reload the page and the network monitor should start filling with dozens of URLs in the order that Firefox requests them. After it calms down, you can scroll down, or click the header for the Domain column to sort by site, and look for requests to these domains. They were called in this order in my little test, amongst a ton of other things: * connect.facebook.net (script - js) * static.ak.facebook.com (html) * s-static.ak.facebook.com (html) * www.facebook.com (html) * fbstatic-a.akamaihd.net (images and scripts) * fbcdn-profile-a.akamaihd.net (images) For example, if there's no request to connect.facebook.net, then a script blocker or tracker blocker may be kicking in. If there's no request for the html pages, then the script may be failing or some other kind of block might be in effect. Note: I stay logged out of Facebook, so being logged in might have some influence on this that I'm not aware of.