Is there a search engine selected in "Options/Preferences -> Search" ?

• https://support.mozilla.org/en-US/kb/use-search-bar-firefox

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• do NOT click the "Refresh Firefox" button on the Safe Mode start window
• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

When I open the 'OPTIONS' window, it will not let me open the 'SEARCH' tab, as I keep on clicking on search, nothing happens, all the other choices work ok.

Did you try Firefox Safe Mode?

I have no idea how to put mozilla in safe mode, can you give me some hints?

You can use one of these to start Firefox in Safe Mode:

• Windows: hold down the Shift key while starting Firefox
• Mac: hold down the Options key while starting Firefox
• Help -> Restart with Add-ons Disabled

See also:

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

Awesome ! I open mozilla in safe mode and was able to pick a search engine, closed and reopened it, looks like everything is back to normal. Thank you very much. Hugo

You're welcome.

Can you post a list of your extensions?

See:

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

I don't know what 'extensions' are.