There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

Websites don't load - troubleshoot and fix error messages

http://kb.mozillazine.org/Error_loading_websites

• MOZILLA_PKIX_ERROR_MITM_DETECTED
• uses an invalid security certificate SSL_ERROR_BAD_CERT_DOMAIN
• configured their website improperly

How to troubleshoot the error code "SEC_ERROR_UNKNOWN_ISSUER" on secure websites https://support.mozilla.org/en-US/kb/troubleshoot-SEC_ERROR_UNKNOWN_ISSUER

It's not my antivirus as it seems to work in Internet Explorer. Also it's not displaying images either which is a problem when I need to print out a shipping label in amazon for return and it refuses to display what I need to print at all. I've tried changing the image settings in about:config with no result.

https://support.mozilla.org/en-US/kb/fix-problems-images-not-show

https://support.mozilla.org/en-US/kb/fix-video-audio-problems-firefox-windows

Make sure you are not blocking content.

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

One issue that seems more common lately is Firefox's Tracking Protection feature. When it is blocking content in a page, a shield icon will appear at the left end of the address bar next to the padlock icon. This article has more info on managing this feature: Tracking Protection {web link}

I've tried safe mode and it still insists on disabling all images on Amazon which is a issue as I need to be able to actually see images when I'm doing refunds as I need to print the information to send the stuff back. I can view them using Google Chrome but I'd rather not have Firefox and Google Chrome on-my system due to trying to make as much harddrive space available for other programs. Same with the blocking Microsoft error.

The problem is weboutlook is picky which browser access it and it's best to use IE as you did to keep it working correctly. I know this because firefox when I used it at work incorrectly display outlook emails.

That's great but this is only a recent thing as far as I can tell. So if weboutlook is being picky it's strange that it decided all of a sudden to start being picky. I'd try hard-resetting Firefox but last time I did that I lost all my bookmarks and add-ons and geting them back was a hassle I'd rather avoid.

Back up and restore information in Firefox profiles.{web link} I use an add-on that makes backups of my user profile, Just In Case. Unfortunately, it is not compatible with the current Firefox.

Every now and then, open the profile folder and create a copy of the current profile as is to another location on your hard drive. This way you will have a backup.

If you do this each day, you will not lose much data. This should be done with Firefox Closed.

Note: In case you need to restore from these backups, you may need to overwrite old or corrupted files.