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:

• 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. Thank you!

Hi Richard, Thought I would chime in with a couple of comments. I have Jessie installed myself. If problems continue a screenshot may help.

• How do I create a screenshot of my problem?

Also be aware if now, or at a later date, you have problems with the unsupported nosquint, that there is now a no squint plus:

• https://addons.mozilla.org/firefox/addon/nosquint-plus

By the way Not too sure why your sytem details in the forum (towards top, left edge) are displaying as a plugin

Shockwave Flash 11.2 r202NoSquint 

My Firefox in Jessie seems ok, so this issue may not be a general Firefox bug

This strikes me as being a problem with Firefox layout, not anything else. So before I continue with generic approaches (most of which have been tried), I am going to be dragged kicking and screaming into web page development; I downloaded DOM inspector and will modify the dimensions of the elements in the header. I think that is what will work. I find it difficult to believe (I've been wrong before) that a different look in the header has anything to do with add-ons that I have installed, as they all address the text or graphical elements in the area below the header. If this doesn't succeed I will get back to you. Thanks for the response.

A screenshot may have helped. NoSquint may modify both web page content and the User Interface of Firefox. (nosquint is also no longer supported & now buggy)

Firefox itself has many built in tools, keyboard shortcut

Ctrl+Shift+C 

will bring up the inspector.

• https://developer.mozilla.org/docs/Tools/Keyboard_shortcuts#Page_Inspector
  • https://developer.mozilla.org/docs/Tools/Page_Inspector

You may also be interested in:

• Pre release versions have a DOM inspector https://developer.mozilla.org/docs/Tools/DOM_Property_Viewer
• The Bowser Console may be what you need, but is off by default. See https://developer.mozilla.org/docs/Tools/Browser_Console#Modifying_the_browser_UI

The problem is still there with NoSquint disabled. You mentioned it is not supported; I just updated Firefox and when it checked the add-ons for compatibility, it passed NoSquint.

Again, I am looking at DOM inspector to modify the header elements first, before I reach for something else. The problem is not a big priority anyhow. I have a number of bugs to fix that are natural occurences in Debian and to a lesser extent in Firefox. Firefox has never really been stable. I find myself continually having to refresh it. That said, I haven't seriously considered any other options except possibly Opera, because of my philosophical viewpoint about open source.

And I know Opera doesn't follow GNU or Open Source guidelines; I just happen to like it because it's like a plucky little upstart.

The problem with nosquint is that its own developer no longer provides support and updates. Currently it is on the Firefox blocklist due to breaking zoom addons.mozilla.org/firefox/blocked/ As I mentioned earlier consider nosquint-plus as an alternative.

Firefox has never really been stable. 
I find myself continually having to refresh it. 

I do not need to constantly Refresh Mozilla Firefox or Iceweasel in Debian. The Refresh removes addons and resets some settings. What it is doing is removing some of your changes. Possibly you need to discover what changes you are making that causes this stability problem.