You can check for problems with current Shockwave Flash plugin versions and hardware acceleration in Firefox 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 (Windows Vista and later)
  https://support.mozilla.org/kb/adobe-flash-protected-mode-firefox
• disable hardware acceleration in the Flash plugin
  https://helpx.adobe.com/flash-player/kb/video-playback-issues.html
• disable hardware acceleration in Firefox
  https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration

See also:

• http://kb.mozillazine.org/Flash#Troubleshooting

What websites are you having problems with? What kind of problems?

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache and

• Remove Cookies
  Warning ! ! This will log you out of sites you're logged in to.

Type about:preferences<Enter> in the address bar.

• Cookies; Select Privacy. Under History, select Firefox will Use Custom Settings. Press the button on the right side called Show Cookies. Use the search bar to look for the site. Note; There may be more than one entry. Remove All of them.
• Cache; Select Advanced > Network. Across from Cached Web Content, Press Clear Now.

If there is still a problem, Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?

Then restart.

Absolutely none of those worked. I even tried to open a .swf game from my pc in Firefox and it came up blank.

Yes I uninstalled flash using the uninstaller and reloaded it.

ok I started in safe mode everything is working now I get to figure out which add-on is causing this all again. Process of elimination. Be back in 2 days.... many add-ons. :/

Ok what was causing it.

It was the 2nd add-on I disabled (First Classic Theme Restorer)

The Cause Firebug Extension.

https://addons.mozilla.org/en-US/firefox/addon/firebug/

That was very good work. Well Done.

FredMcD said

That was very good work. Well Done.

Well I Since I have so many add-ons I learned to start disabling the "heavy" add-ons with the most features. Then any add-ons related to issue I am having.

Also Using the Error Console , open that, then clear out of any messages and then try to preform the issue I am having to see if any message pop up on it

I seem to have fixed this problem accidentally, and would like to share. After updating to Flash 21.0.0.226, it was always disabled. I would enable then even refreshing the Add-ons Manager page would show the plug-in as again disabled.

As a test, I archived my current profile and reloaded the default profile, which I keep archived for testing and other emergency purposes. (Firefox then updates the profile pathname in profiles.ini: Path=Profiles/XXXXXXXX.default)

After starting and quitting FF with the default profile, I then went back to my current active profile. I then had to manually update the profile pathname back to my active profile.

For some reason, this fixed the problem.