You can check for recently installed suspicious or unknown extensions with possibly Search or Incognito in their name.

• https://support.mozilla.org/en-US/kb/disable-or-remove-add-ons
• https://support.mozilla.org/en-US/kb/uninstalling-toolbars

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

Hi freddyo, in Firefox 57, add-ons aren't supposed to be able to create new toolbars in the toolbar area. If you click in the page and use zoom (hold down Ctrl and tap the + key a few times), does the unwanted toolbar also zoom? If so, that suggests something is injecting into the page. Hopefully the investigation cor-el suggests will allow you to kick it to the curb.

If that doesn't clean it out, you may want to check for a Firefox program folder infection. That would be in one of these locations (varies for 32-bit / 64-bit):

• C:\Program Files\Mozilla Firefox\defaults\pref
• C:\Program Files (x86)\Mozilla Firefox\defaults\pref

A file named channel-prefs.js is normal. Any other file is suspicious. Remove any such files to a neutral location for further analysis at your leisure, or bury them in the Recycle Bin. Please do not double-click .js files as that will execute them as Windows system scripts. You can right-click > Edit or right-click > Open With to view them in Notepad.

There seem to be more of those in the past month.

Thanks for your suggestions. It turns out that the Bing search bar is part of my default web page https://www.msn.com/en-us/money