This could be the work of an add-on trying to protect your settings. It could also be your protection program verifying the change.

A suggested above, one possible culprit would be an extension. You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then cast a critical eye over the list on the right side. All extensions are optional. If in doubt, disable.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

It is also possible that your security software is doing this.

Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

I tried re-booting in safe mode with networking on (F5), but networking did not come up and I could not bring up. I also received a popup at start up which said some start up app could not start under the system administrator and that I needed to sign on with a different ID. However, I had signed on with my ID (which has administrator privileges.)

Also I was able to start Firefox without networking and received the same problem prompts as before with no additional information as to why.

I tried disabling all of my extension (only 3 were enabled.) That did not help, but it reminded me that the problem only began after I had installed a flight status app (from Google I believe.) This app changed my home page to a Google page and option to show it on Firefox start up. When I realized this, I removed the app and reset my options to what they had been before. It's probable that the app I removed changed something else. Does anyone know what that could be?

See my last reply.

Can you post a screenshot of the message you're getting. Maybe someone will recognize it and be able to associate it with a particular program.

This article has tips on how to capture a screenshot: How do I create a screenshot of my problem? Please cut out or blur any sensitive information in the image before attaching the file to a reply.

Can you check your history to see exactly what it is that you downloaded? That may help with discovering bundled malware.

And of course you can supplement your regular security software with some on-demand scanners, such as the free ones listed in our support article: Troubleshoot Firefox issues caused by malware.

From my history I believe the link for the app I installed was: http://www.flightstatuslive.com/lp/?v=airline&airline=DELTA&code=DAL&utm_source=adcenter&utm_medium=cpc&utm_term=delta%20flight%20status&utm_campaign=FSLnew

However, also from my history, it may have been: http://free.getflightinfo.com/index.jhtml?partner=^C4P^xdm104&s1=flightstatuslive-2&s2=airline&s3=2&s4=pc|firefox+v46&s5=FSLnew&theme=1ab09012015

Below is the prompt I receive every time I start Firefox.

Mindspark; Pconverter Toolbar ? Disable this.

I had already tried this, but this time I disabled it and re-booted the computer. The problem still existed. I also, thought it might have something to do with re-syncing the application with other systems. Therefore I removed all syncing options without solving the problem. There must be some flag somewhere that needs to be re-set to solve the problem. I believe that this flag should be re-set the first time I reply to keep the new setting. I am not sure what software is responsible, but I am pretty sure it is a bug in whatever software creates the popup requiring me to reply.

I also question why the popup says that another application changed the home page when I did the change myself using the Firefox application. That suggests that the problem may be within Firefox itself when I made the change.

Mindspark Interactive is well known as a purveyor of Malware / PUP. https://www.pcrisk.com/removal-guides/7420-mindspark-toolbar

The place to start removing garbage like that is the Windows Control Panel, and then go to the Web Browsers to remove it from each browser.

I recommend a thorough scan for other Malware that you may not even be aware of, and get of that stuff, too.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one. Windows 8 has antivirus built-in already.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

Extensions that do not have a "Remove" button are installed globally by other software and are not under control of the Firefox extension manager. Globally installed extensions are usually found via a registry scan or are installed in a location that Firefox scans for installed extensions.

• https://developer.mozilla.org/Installing_extensions
• https://developer.mozilla.org/Adding_Extensions_using_the_Windows_Registry

Extensions installed this way need to be removed via the settings (options/preferences) of the program that has added this extension or this program has to be uninstalled via "Control Panel > Programs". In Firefox you an only disable such an extension.

You can find the location of extensions that are installed globally in the extensions.json file in the Firefox profile folder.

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

You can open the file in the Scratchpad ("3-bar" menu button or Tools > Web Developer). Click the "Pretty Print" button to format the file for readability.

• https://developer.mozilla.org/Tools/Scratchpad

None of the suggestions have helped, but the problem no longer occurs. I suspect it was fixed by a Windows update that was applied a couple of days ago.

I do appreciate receiving the suggestions anyway! Thanks to all!