Hello,

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:

• In Firefox 29.0 and above, click the menu button , click Help and select Restart with Add-ons Disabled.
• In previous Firefox versions, click on the Firefox button at the top left of the Firefox window and click on Help (or click on Help in the Menu bar, if you don't have a Firefox button) then click on 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.

It worked! After "restart with add-ons disabled" the problem was gone! But I didn't really want to disable all my add-ons, forever, so I restarted the traditional way, and began taking a close look at my list of add-ons. (I'm afraid I have a tendency to install add-ons that sound neat, without really knowing what they'll do. I just figure I'll study them closely some other time....) Well, I spotted an add-on that was clearly the source of the problem...and, being too impulsive, as usual, I removed it, without first making a note of the name. So all I can tell you is that the name started with php. somethingsomething and ended with Timeout. I have no idea why I installed it in the first place, or what I thought it would do for me. Duh! But I'm really grateful for the help and guidance that fixed this problem! (And I will be much more cautious in the future.) THANK YOU!!!