Check the date and time in the clock on your computer: (double) click the clock icon on the Windows Taskbar.

• https://support.mozilla.org/kb/Secure+Connection+Failed

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

Clear the cache and cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

As mentioned in the original trouble report most of these things have been done multiple times and none of them help.

This problem is on my work computer and is affecting both Chrome and Firefox. I have also recently noticed that images from Flickr will not load properly.

As everything works properly on my home computer there must be a system setting somewhere that is wrong (or my IT department changed things, although that seems unlikely as most sites work properly).

LAST RESORT ! ! Reset Firefox

Firefox was completely uninstalled, including user data, and reinstalled. This did not help. Not sure if this is the same as a reset though.

The most common reason for this, assuming your clock is correct, is malware that intercepts your secure connections with an invalid security certificate. The malware is able to transparently slip its bogus certificates into the Windows certificate store used by IE, but can't as easily slip them into Firefox's certificate file.

Has Firefox presented any error pages indicating a certificate problem since this problem began?

If you click the padlock icon when you're viewing https://addons.mozilla.org/firefox/ , click More Information, and then click View Certificate, what is listed in the "Issued by" section of the dialog?

Here is a screenshot of the certificate page

Silly question, have you checked you system clock? Sometimes the problem like this turns out the clock was not correct. Make sure the computer is set to check the atomic clock automatically.

Yes, my system clock is correct. It is currently at 9:08AM ET on 5/20/2014

The Add-ons site uses these style sheet:

• https://mozorg.cdn.mozilla.net/media/css/tabzilla-min.css
• https://addons.cdn.mozilla.net/media/css/zamboni/impala-min.css?build=8c23634

Can you load those directly (should just look like a bunch of text all run together), or do you get an error?

If those load and you then refresh the Add-ons page, does it get styled properly?

Is there any content showing a size 0 (zero) in the Network tab in the Web Console (Firefox/Tools > Web Developer)?

You need to refresh the page via Ctrl+F5 to bypass the cache.

• https://developer.mozilla.org/Tools/Web_Console

The CSS links do not open properly in Mozilla but they do in IE.

So far I have identified 4 problems I am having.

The addons page will not work correctly.

Images on Flickr do not load correctly, but Photobucket is no problem. (Both work in IE)

www.coinbase.com and www.btc-e.com do not even attempt to load in FF, but do load in IE.

Chrome seems to have the same issues that FF does.

Do Chrome and Firefox connect through a filter that IE bypasses? Or to put that the other way around, does IE connect differently than other browsers?

If you open the web console (Ctrl+Shift+k) and then in that tab reload the sites that do not load, what response code is Firefox getting from the server according to the console? (For example, 404 Not Found, 500 Internal Server Error, etc.)

I am not aware of IE being passed through filters differently than FF or Chrome.

The Web Console gives this when trying to open coinbase:

GET http://www.coinbase.com/ [HTTP/1.1 301 Moved Permanently 203ms] GET https://www.coinbase.com/ [31ms]

That is all that is there and it does not attempt to do anything else.

btc-e gives:

GET http://www.btc-e.com/ [HTTP/1.1 302 Moved Temporarily 62ms] GET https://btc-e.com/ [78ms]

Seems to be a problem with HTTPS sites, but I'm struggling to come up with something else to check. Does your IT have any insight?

Thank you for all of your help. I am going to stop worrying about it and just work around it. I am supposed to be getting a new PC in the next month or so and hopefully that will fix things.

I have not asked IT about it as they do not support Firefox, but I despise IE so I use FF anyway.

As far as it being HTTPS related, I have no issues with many HTTPS sites including my banks, credit cards, Ebay, Amazon, PayPal, etc...

Very odd problem.