I had the same problem once. If I remember correctly you have to go to Tools -> Add-ons, and then remove the Ask add-on.

Tools / Extensions then Remove.

I am using firefox 5.0, please advice accordingly. Thanks

Last week i updated my firefox to 5.0. version. My default home page is Mozilla page. After typing a word in search bar...SURPRISE ! Ask.com Web Search is opened instead of google !! Why ??!...and How do I remove it ?!!

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

Try to delete the file webappsstore.sqlite in the Firefox Profile Folder

• http://kb.mozillazine.org/Profile_folder_-_Firefox

Sorry, but none of the options does not help me! I returned to Firefox 5 to the previous version, hoping he returns everything as it was, but the same problem remains. After opening firefox (Mozilla Firefox Start Page), type in the search box and instead to open google search, open the Web Search Ask.com! And that's starting to annoy me, especially since I already lost a day and night trying all options to remedy the situation! Someone still has a valid solution? Ah, I forgot ... ask.com web search is no longer between my add-ons, i deleted. Is also deleted from "Manage Serch Engines", so ...left something to be done??? Thanks in advance..!

Unfortunately, it is becoming more and more common for these kinds of "extras" (toolbars, security scanners, etc.) to be added to your browser/system/desktop when adding or updating other software, some from very well-know software vendors. You must carefully read information before downloading any "free" software and be very alert during the install process for any opportunity to opt-out of "extras" being installed.

If you have the Ask Toolbar

• First try to disable or uninstall the Ask Toolbar in Firefox via "Tools -> Add-ons -> Extensions". See:
• Disable or remove Add-ons
• http://kb.mozillazine.org/Uninstalling_toolbars
  
• In some cases, you may need to uninstall the Ask Toolbar using Windows Control Panel .
  • See Cannot uninstall an add-on - Uninstall from Windows Add/Remove Programs.

You MAY need to reset a preference
You may also need to reset preferences related to Ask.com via about:config, specifically the keyword.URL preference, if when typing a word or two in the URL/Address/Location Bar takes you to Ask search -

• Open a new tab or window.
• Type about:config in the URL/address bar and press the Enter key
• If you see a warning, accept it (promise to be careful)
• Filter = keyword.url
• Right-click on the preference below the Filter, and choose Reset
• Restart Firefox (File > Restart Firefox)
• See: http://kb.mozillazine.org/Keyword.URL for details.

You MAY need to reset your homepage if some search page that you do not want or expect opens when you start Firefox. Firefox can open multiple home pages. Home pages are separated by the "|" symbol.

• See: http://support.mozilla.com/en-US/kb/How+to+set+the+home+page

Also see:

• http://kb.mozillazine.org/Problematic_extensions#Ask_Toolbar

The previous post has it, but lets simplify it!! Resetting the preferences fixed my issue. Firefox>> Help>> Addons Disabled>> Reset Preferences>> Restart Firefox. Bang issue resolved!!

omnieckert:

Simple, if and only if, you want to reset ALL preferences back to the installation defaults that you have modified for other reasons and affecting other aspects of your Firefox installation.