This sometimes sneaks in with a Java update, since it is something you have to opt out of during that process.

This might seem like overkill, but I suggest a brief detour here:

(1) Open the Windows Control Panel, Uninstall a Program (or for XP Add/Remove Programs). After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here.

(2) Open Firefox's Add-ons page using either:

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

In the left column, click Plugins. Set nonessential and unrecognized plugins to "Never Activate".

In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

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.

(3) With the above removed, you can restore your own preferences. As applicable:

(A) Preferred search engine. Change the icon at the left end of the search bar. See: Search bar - add, change and manage search engines on Firefox.

(B) Home page. These articles have more details on how:

• Startup, home page, tabs, and download settings
• How to set the home page

(C) New Tab page. There's a hidden setting for this:

(i) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(ii) In the search box above the list, type or paste newtab and pause while the list is filtered

(iii) Double-click the browser.newtab.url preference and enter your preferred page:

• Page thumbnails (default) => about:newtab
• Blank tab => about:blank
• Built-in Firefox home page => about:home
• Any other page => full URL to the page

Press Ctrl+t to open a new tab and verify that it worked. Fixed?

Success?

You can use the SearchReset extension to reset some preferences to the default values.

• https://addons.mozilla.org/firefox/addon/searchreset/

Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons).

You can open the about:config page via the location/address bar and search for prefs that refer to k.com. You can reset user set (bold) prefs via the right-click context menu to the default value.

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

If you do not keep changes after a restart or otherwise have problems with preferences, see:

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