That issue can be caused by an extension that isn't working properly.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

How do I "start Firefox in Safe Mode"? Sounds complicated.

In the Run... (or press Windows key + R) dialog box type firefox -safe-mode and OK. If that doesn't work Search for firefox.exe and in the results right-click firefox.exe > Properties, copy the Location by highlighting it and then instead of just firefox prefix that location in double quotes eg. "C:\Program Files(x86)\Mozilla Firefox\firefox.exe" -safe-mode

If the problem persists in Safe Mode, you may want to check if the Alt keys of the keyboard are stuck. The combination of Alt + D is a shortcut to highlight the address bar.

When I look p properties, I get this: C:\Program Files (x86)\Mozilla Firefox

Then what?

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -safe-mode

First make sure that Firefox is not running and then type the above into the Run... (Windows key + R) dialog box and click OK. This will start Firefox in Safe Mode. You can read more about the Safe Mode, the different ways to start Firefox in Safe Mode and troubleshooting tips in the links given by cor-el.

In Firefox 4+ versions you can use one of these to start in Safe mode:

• Help > Restart with Add-ons Disabled
• Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)

• https://support.mozilla.com/kb/Safe+Mode

I am really lost. If I started Firefox in Safe mode, then what? more complicated instructions to follow? I don't quite get what it is that I need to do. I gather that I need to track down which extensions is the culprit, and uninstall/delete it? I'm not sure I have the experience level or skills to do this. All I want is to stop the cursor from jumping to the address bar whenever I try to type key word in Google search engine!

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

This seems to be caused by the add-on "New Tab Homepage". Disabling this and using NewTabURL (2.2.3) seemed to solve the problem for me.

HTH