Check the Properties > Shortcut -> Target line to see if those three URL's were added to the desktop shortcut. That would override whatever you set in Firefox prefs, but wouldn't be used when you hit the Home button.

The urls don't appear in target. The home button also causes a connection to the 3 urls. prefs.js seems to get rewritten by firefox when it starts, according to Russinovich's process monitor.

What is the URL of the one that can't be changed?

Have you run any anti-malware programs? Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

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!

How does the home page pref appear on the about:config page?

• browser.startup.homepage

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

None of the urls change ; you can change any or all , & the original set comes right back.

This laptop has been extensively tested for malware including boo time Avast & Kaspersky. If after that it has malware on board, I'd have to throw everything away, wipe the disk, & install something different - what else could I do? I don't think that is it tho. It's configuration. Malware whose sole job is to protect a unique set of urls is strange.

You can change it all you want, but the original home page set comes right back on restart - or as soon as you click on the home button.

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

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

• Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

There was a mozilla.cfg in program files (x86) that had the home pages embedded in it. This wasn't indexed by the windows file indexer for some reason, so when it didn't show it when I looked for it, I didn't know it really was there.

Where did you find that file? I seem to have the same problem, but with only two web pages.

Check if there is a mozilla.cfg file present in the Firefox program folder to initialize or lock prefs.

• (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
• (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

This also involves the presence of a .js (JScript) file in the "defaults\pref" folder that specifies to process this mozilla.cfg file.

If there are .js files present in the "defaults\pref" folder apart from the channel-prefs.js file that sets app.update.channel then open this file in a plain texteditor like Notepad (Mac: TextEdit) and please post its content. Also please post the content of the mozilla.cfg file.

There shouldn't be a mozilla.cfg file present unless you've created it yourself to initialize some prefs.

If you have this mozilla.cfg file then best is to do a clean reinstall and delete the Firefox program folder before reinstalling a fresh copy of Firefox.

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

You can find the full version of the current Firefox release (42.0) in all languages and all operating systems here:

• https://www.mozilla.org/en-US/firefox/all/