Hello,

Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• On Windows you can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac you can open Firefox 4.0+ in Safe Mode by holding the option key while starting Firefox.
• On Linux you can open Firefox 4.0+ in Safe Mode by quitting Firefox and then going to your Terminal and running: firefox -safe-mode (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the 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 other users who have the same problem.

Thank you.

Do you recall what you changed in about:config?

What happens when you click the links on the problem site: nothing? Server not found?? If it's a site that worked before in Firefox, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

Alternately, you also can clear Firefox's cache completely using:

orange Firefox button (or Tools menu) > Options > Advanced

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click and choose View Page Info > Security > "View Cookies"
• Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies"

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page. Does that help?

Note that your System Details List shows that you have obsolete preferences from previous Firefox versions that are no longer supported.

You can delete the prefs.js file and possible numbered prefs-##.js files and a possible user.js file to reset all prefs to the default value or edit the prefs.js file and remove the corresponding lines or reset these prefs to the default value via the right-click context menu.

Also note that your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there.
you can check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

The only .js files I can find (in the Mozilla Firefox folder and sub folders) is nsprotector.js and channel-prefs.ljs.

I did find the user.js files and deleted them. Didn't help. However, it works in safe mode so I will have to find out what extension(s) cause(s) the problem.

Do you recall what you changed in about:config?

    Unfortunately, no.  I just followed the instructions.

What happens when you click the links on the problem site: nothing?

    It goes to a page where a video screen is supposed  to be.  Sometimes there is no screen, sometimes there is a screen but no controls to start the video.

Server not found?? If it's a site that worked before in Firefox, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

    One of the sites worked before.  I will try clearing the cache.  
    One site, http://soliloquywp.com/, when I clicked on the play button in the "Create your next ...... screen it went to a black screen but nothing played.

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

    No difference.

Alternately, you also can clear Firefox's cache completely using:

orange Firefox button (or Tools menu) > Options > Advanced

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

   right-click and choose View Page Info > Security > "View Cookies"
         Didn't help.

   Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies" 

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page. Does that help?

Thanks for the assistance. Ill keep trying.

It worked in Safe Mode. I'll investigate further. Thanks.

To find the user.js file, you can follow the steps in this article: How to fix preferences that won't save.