Reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl+0 (zero); Command+0 on Mac)

• http://kb.mozillazine.org/Zoom_text_of_web_pages

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.

Delete a possible user.js file and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js or if there only are a few you can reset involved prefs on the about:config page via the right-click context menu to the default value.

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

Thank you for this. I had already tried this, however and it has made no difference. If it's of any further help, I should mention that this change in display has occurred only today and without any manual intervention or third party software installation or uninstallation. I also have a laptop on the same network that uses the same operationg system (Windows 7) and the same browser (Firefox's current version) but the search results display change has not manifested itself on that machine.

Start Firefox in Safe Mode

At the top of the Firefox window, click the Firefox button, go over to the Help menu and select Restart with Add-ons Disabled....

Firefox will start up with the Firefox Safe Mode dialog.

Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.

Clicking the Start in Safe Mode button will temporarily disable your extensions and themes, turn off hardware acceleration and reset toolbar and button customizations. When you leave Safe Mode and start Firefox up normally.

Diagnose Firefox issues using Troubleshoot Mode

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

If you have made changes to Advanced font settings like increasing the minimum/default font size then try the default minimum setting "none" and the default font size 16 in case the current setting is causing problems.

• Tools > Options > Content : Fonts & Colors > Advanced > Minimum Font Size (none)

Make sure that you allow pages to choose their own fonts.

• Tools > Options > Content : Fonts & Colors > Advanced: [X] "Allow pages to choose their own fonts, instead of my selections above"

Thank you for this. The same problem occurs in Safe Mode.

Have you tried to zoom out the page? <Control> - (minus)

If you can run a search for, say, Mozilla Firefox, and grab a screen shot I think that would be helpful, and volunteers can compare their own results on the same search engine. Please include the address of the search results page as a link in your reply for easy clicking.

Yes, but to no avail. I can make what's displayed smaller or larger but cannot alter the vertical spacing.

Sorry for the delay in responding. I had one of those dreaded "blue screen" manifestations early this morning and have been engaged in rescue operations since then. These have included a couple of Windows troubleshooting procedures, a successful Malwarebytes scan and a run of CCleaner. I have noticed that the condition that I reported within Firefox's search results page display has subsequently rectified itself as easily and inexplicably as it materialised yesterday!

I'll watch points, of course, over tghe next days and weeks but all now seems to be back to norma for the time being. Many thanks to all of those who tried to help with this.