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.

Hello,

Thank you for your response. I ran your fix, and the exact same issue still presented identically in Safe Mode as in normal operations. I attempted to load websites with embedded .swf files, and I also attempted to run files saved on my computer. All had the same problem still.

The fact that the issue still occurs while in safe mode tells me that the issue is most likely not caused by an add-on that has been installed on Firefox.

Some problems with Flash video playback can be resolved by disabling hardware acceleration in your Flash Player settings. (See this article for more information on using the Flash plugin in Firefox).

To disable hardware acceleration in Flash Player:

1. Go to this Adobe Flash Player Help page.
2. Right-click on the Flash Player logo on that page.
3. Click on Settings in the context menu. The Adobe Flash Player Settings screen will open.
4. Click on the icon at the bottom-left of the Adobe Flash Player Settings window to open the Display panel.
   
   The image "fpSettings1.PNG" does not exist.
   
5. Remove the check mark from Enable hardware acceleration.
6. Click Close to close the Adobe Flash Player Settings Window.
7. Restart Firefox.

This Flash Player Help - Display Settings page has more information on Flash Player hardware acceleration, if you're interested.

If the above does not solve the issue, can you please test to see if the Adobe Flash file will load in the default Internet Explorer that is included with your version of Windows? Tests cannot be run from Google Chrome, as Chrome comes with a built-in flash player and cannot be used to determine whether there is an issue with flash on your computer.

Hello,

I visited the link you supplied, and I cannot see any Flash logo anywhere. Every place where there is supposed to be a Flash file, is instead completely blank. Right-clicking on those spaces instead produces the standard Firefox context menu.

Also, attempting to open local Flash files in Internet Explorer resulted in it simply asking whether I wanted to open or save the file in an infinite loop. I then attempted to load a speed testing website which has been failing to run in Firefox, and that site informed me that I needed to have Flash installed for it to work. I reinstalled Flash, and the site now runs properly in Internet Explorer. It still fails to run in Firefox. Attempting to run local files in Internet Explorer after reinstalling Flash again leads to a blank white screen.

Can you please ensure that the Adobe Flashplayer plugin is not disabled on Firefox? To do so, please follow these steps:

1. Select Add-ons from the Tools drop-down in the menu bar
2. Select the Plugins from the sidebar
3. Locate Adobe Flash
4. Select Always Activate from the drop-down menu
5. Restart Firefox

See if this repairs the issue. If not, please uninstall Adobe Flashplayer and try downloading and installing Shockwave Flash for Firefox.

I suppose I should have double checked this right off of the start, but can you please ensure that you are downloading and installing the Flash Player for the correct operating system and for Firefox from this website?

Hello,

I do not have an Adobe Flash option when I go into that menu. I do have Shockwave Flash however, and that is set to Always Activate. In addition, yes, that is the website I have been downloading and reinstalling Flash from. Just to be certain, I went ahead and downloaded it again and ran it from the link you supplied, to no avail.

I have uninstalled and reinstalled Flash previously as well.

Try disabling graphics hardware acceleration. Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches.

You will need to restart Firefox for this to take effect so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

Then perform these steps:

1. Click the menu button and select Options on Windows or Preferences on Mac or Linux.
2. Select the Advanced panel and then the General tab.
3. Uncheck Use hardware acceleration when available.
4. Restart Firefox and see if the problems persist.

Did this fix your problems? Please report back to us!

If the problem is resolved, you should check for updates for your graphics driver by following the steps mentioned in these Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

Thank you.

Hello,

I disabled Hardware Acceleration, and the problem still persists. Quite the conundrum.

When you load a page with the SWF content on it, is there a plugin icon on the left side of the address bar? If there is, can you please see if it is telling you to allow Adobe Flash or Adobe Shockwave?

Make sure your Java (Not JavaScript) is up to date Verify Java and Find Out-of-Date Versions {web link}

Version 8 Update 60 Release date August 18, 2015

No, there is no plugin icon there. By comparison, there is a plugin icon on the page that FredMcD linked to, for Java.

Also, on the topic of that page, yes my Java is up to date.

Thank you for your continued assistance with this.

Have you checked to ensure that there is no malware on your computer? Since the issue occurs on more than just Firefox and started so suddenly, it seems like this might be the issue. Even if you have an anti-virus software active on your computer, certain malware cannot be detected. Can you please run some of the free tools from this list?

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner
• Hitman Pro
• ESET Online Scanner

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

I recommend and use AdwCleaner myself and find that it does a great job of cleaning your computer from malware.

Amenephis said

On websites with a background I can see the background through where the .swf file should be. This includes opening locally saved files as well as every website with a .swf file that's supposed to play.

Please post some of the links where you are having problems.

http://www.speedtest.net/ is the site I've been using, but I have identical issues on several other sites, including the Flash site itself. I'll run the antivirus stuff in a moment.

I installed and ran every single scanner you linked to there, as well as Spybot S&D just for grins since I had forgotten to reinstall it since I last formatted my computer...none of them came up with anything.

You can check for problems with current Shockwave Flash plugin versions and try this:

• make sure you have the latest Flash version:
  http://www.adobe.com/special/products/flashplayer/fp_distribution3.html
• check for updates for your graphics drive drivers
  https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration
• disable protected mode in the Flash plugin (Flash 11.3+ on Windows Vista and later)
• disable hardware acceleration in the Flash plugin
• disable hardware acceleration in Firefox
  https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

See also:

• http://kb.mozillazine.org/Flash#Troubleshooting
• https://support.mozilla.org/kb/adobe-flash-protected-mode-firefox

Boot the computer in Windows Safe mode with network support (press F8 on the boot screen) to see if that has effect.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/

That got it! Disabling Protected Mode in Shockwave Flash caused everything to suddenly start working again. Thank you so much!