Hi, it would be worth testing with your extensions temporarily disabled, or you could try try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

The OP said he's already tried using it in Safe Mode, and it was still happening. I can't log in to various sites, as the pop up login windows show up blank! As does the Facebook Share extension. And this was happening even before I added that extension, and was why I did add it. This is frustrating, as there's no other way to sign in to some of these sites.

Load the web page. After the page is loaded, click the down arrow next to the AdBlock icon. Now select Disable on <web site>.

Forum; Adblock Plus Forum {web link} https://adblockplus.org/ Homepage

What security software do you have?

Create a new profile as a test to check if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

FredMcD said

Load the web page. After the page is loaded, click the down arrow next to the AdBlock icon. Now select Disable on <web site>. Forum; Adblock Plus Forum {web link} https://adblockplus.org/ Homepage

I'm now able to enter popup login windows, and the Facebook Share is working (didn't do anything, but I think FF did update since I first had the issue), however, when I'm on the CBS.com site, I can't play any videos, as I keep getting an error message that I need to disable my ad-blocking software. Well, it IS disabled, that site is white-listed, and I'll manually select to disable it on that particular page, and still nothing plays. I have to open up Chrome, do nothing, and it will work fine. So, it's obviously not a firewall or anti-virus issue, since using a different browser wouldn't change that... I'm stumped.

Hello,

In order to better assist you with your issue please provide us with a screenshot. If you need help to create a screenshot, please see How do I create a screenshot of my problem?

Once you've done this, attach the saved screenshot file to your forum post by clicking the Browse... button below the Post your reply box. This will help us to visualize the problem.

Thank you!