if your manual changes don't 'stick' after a restart of the browser, please look out for any suspicious extensions (like 3rd-party-toolbars or things you have not installed intentionally) presently installed under firefox/tools > addons > extensions or the programs section of the windows control panel and remove those entries.

in case this doesn't solve the issue please try this: go to firefox > help > troubleshooting information > profile folder - "show folder", then a new window will open up. in this window look out for a file named user.js (it might be used to overwrite your custom settings). in case it is present , delete or rename this file and restart firefox afterwards.

Remove a toolbar that has taken over your Firefox search or home page
How to fix preferences that won't save

finally install the search reset addon - it will revert the most common customizations those adware programs do in firefox back to the default: https://addons.mozilla.org/firefox/addon/searchreset/

Try removing the "Default Tab 2.2.41" extension in Add-ons > Extensions.

Then reset your home page, if necessary

• See - https://support.mozilla.org/en-US/kb/How%20to%20set%20the%20home%20page

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
• TDSSKiller - AntiRootkit Utility
• 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.

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

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

Note that the Default Tab 2.2.41 is known malware.

Your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there. you can check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

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

Default Tab is malware/spyware. That extension will "piggyback" with other extensions you downloaded/installed from the internet.

More detailed instructions to remove Default Tab (instructions have worked for other users in the past)

1. With all browsers closed, in Windows Control Panel > Programs and Features (or Add or Remove Programs), if you see "Default Tab" remove it
2. Start Firefox and verify that "Default Tab" is not in Add-ons > Extensions; if it is click to "Remove" then restart Firefox.
3. You may need to set your home page in Firefox if a search page leading to "Search Results" or "My Search Results" appears when starting Firefox - https://support.mozilla.org/en-US/kb/How%20to%20set%20the%20home%20page
4. You may need to remove "Search Results" or "My Search Results" from your list of installed search engines in the Search Bar in the upper right (click on the image at the left end of the Search Bar and choose "Manage Search Engines") - https://support.mozilla.org/en-US/kb/search-bar-easily-choose-your-search-engine#w_removing-a-search-engine
5. Download, install and run the following extension to reset your search engines in Firefox to the default search engines that came with Firefox. Read the add-on page; it will run once then uninstall itself.
   • https://addons.mozilla.org/en-us/firefox/addon/searchreset/
6. You may need to reset a preference if "Search Results" or "My Search Results" is appearing as a search engine every time you open a new tab (follow steps 1-4 below the image to determine what opens when you click to open a new tab; see about:config usage above) - https://support.mozilla.org/en-US/kb/new-tab-page-show-hide-and-customize-top-sites#w_how-do-i-turn-the-new-tab-page-off