Could you try the current release of Firefox? You seem to have a very old version.

https://www.mozilla.org/firefox/all/

Everything else works just fine, so it's not a problem of the version of the browser. In fact, in researching this problem I've seen comments from people who said they couldn't open Facebook on the newest version of Firefox. So far no one seems to have come up with an explanation or solution.

Right, there are many possible reasons for failure and the troubleshooting process is to rule them out systematically.

Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware

I don't have a Windows computer. I use a Mac.

ellen, Facebook recently changed some things, breaking support for old versions of Firefox. You need to update to Firefox 33.0.2 or later. Please do so immediately. Update Firefox to the latest release

Please do not order me to "do it immediately". This type of rhetoric comes across as arrogant and condescending and is not going to win friends or make people want to run and do what you suggest. I do not know whether the latest version of Firefox will even run on my Macbook Pro. My experience is that updating most things just leads to more problems. The only updates that seem to be benign are those provided for Adobe products.

Trying to update my old version of Safari (which worked fine with everything, so I should have known better) hijacked the old version with a new version that wouldn't run on my operating system, so I can't use Safari at all. That's why I switched to Firefox.

I passionately hate the whole spiral of engineered obsolescence when it comes to computer-software interactions. I do not want to buy a new laptop every two years.

It's your choice, of course, what version of Firefox to run. But why stick to a version from April 2012 when you are just starting out with Firefox? It seem arbitrary.

Mozilla openly discloses security vulnerabilities after each update (here), so attackers already know how to use old versions of Firefox to infect a system. Even if you don't like the tone of Tyler's request, you can understand his logic.

If you don't want to use a current version of Firefox, from a security perspective, it would be better to use a current version of a different browser.

Also, from our perspective in providing support, we volunteers can't go back that far in time to debug website problems in a version none of us use any more.

You don't need to buy a new computer to run the new version of Firefox. the reason you need to update is because Facebook introduced a new feature that breaks on old versions of Firefox. Updating not only keeps you safe, it lets you use Firefox. I'm not sure why you don't want to update, but it's a simple and painless process (especially since you are just getting started with Firefox) and will make this problem go away.

You tell me the newest Firefox will run on my computer, but that's exactly what I was told when I installed the newer version of Safari, which doesn't run. I am only OK with installing a new version of software after I am 100% sure that it will run without bugs on my current computer (and that it will run at all). Thank you all for your volunteer time on behalf of Firefox, and Facebook. I will now go elsewhere to look for information.

Right here you can see that Mac 10.6 is in the supported systems for Firefox 33.0.2. https://www.mozilla.org/en-US/firefox/33.0.2/system-requirements/

We also have millions of Mac 10.6 users who use Firefox 33.0.2 every day with no issue, I'm confident you will be able to use it with no issue as well :)