Ask software is often packaged into free downloads, it's their strategy for getting into your browsers. Here's my suggested procedure for tracking down and cleaning up bad add-ons, hijackers, and other troublemakers. I know it seems long, but it's not that bad.

(1) Open the Windows Control Panel, Uninstall a Program (on XP: Add/Remove Programs). After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date (XP doesn't have this, but you can try sorting by "Last used"). 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 Windows "Run" dialog, type or paste
  firefox.exe "about:addons"

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. Bear in mind that all extensions are optional.

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?

(3) You can search for remaining issues with the scanning/cleaning tools listed in our support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.

Can you get control of Firefox again?

Curiously, another user posted a similar question this morning: Search on ebay goes to ask.com but doesn't on internet explorer -- resolved using Firefox's Refresh feature, which removes all your add-ons and resets your custom settings, so it's a bit drastic if you can find a more surgical solution.