Best answer as chosen by user porthome: Tried This...?
Although I'm using Firefox 16.0.2 here, yours should be similar. Open Firefox, then click on "Tools" in the upper left, then choose "Add-ons" from the menu. Once that opens up, click on the "Extensions" tab and look for the "Ask.com" add-on.. If there, delete it. Next, click on the "Plugins" tab and look for the "Ask.com" listing.. If there, delete it as well.
Once that's done, then download, install, update, and run a full scan using the free Malwarebytes spyware removal tool from the link below. Remove anything it finds.
And just a note: If you've recently installed the new Avira free antivirus, it may have included the Ask.com toolbar in your browser by default.. In order to remove it, you'll need to use the Control Panel-Add/Remove Program section, select the Avira program, choose "Change", then "Modify", then UNCHECK all the "Web Protection" and "Avira Search Free" sections.
Hope this helps.