Your image showed

https://www.google.com/search?client=ubuntu&channel=fs&q=firefox&ie-utf-8&oe=utf-8

I am not using Ubuntu at the moment. I am guessing that is a fairly normal URL for such a search but that you have some Firefox addon or some toolbar added to Ubuntu.

What happens next when you click the yes option, or if you click the blue icon on the left. That may give a clue to what it is you have. Obviously you are not getting the proper search results something seems to be intercepting that.

Please try Firefox in its safemode and also look at the list of addons you have installed. Use Menu Button -> Restart with Add-ons disabled and Menu Button -> Addons See also

• Diagnose Firefox issues using Troubleshoot Mode
• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems_disable-all-extensions
  • Unable to install add-ons (extensions or themes)
• How do I create a screenshot of my problem?

P.S. Firefox did at one time give different results depending on whether you typed in to the address bar or the search bar.

It still will in some instances ,because the addressbar (on the left) expects an address, the search bar (on the right) expects a search term. If the address bar gets something that is not a valid adddress, or a short partof an address it will then try to search.

For example if you type in to the address bar "support.mozilla" that may autocomplete to a valid address https://support.mozilla.org

The addressbar also has a few other options and customistions

• Address bar autocomplete suggestions in Firefox

See also:

• http://msujaws.wordpress.com/2014/08/01/faster-and-snappier-searches-now-in-firefox-aurora/

While submitting a one-word query like firefox to your default search engine, for address bar searches, Firefox also makes a DNS query in the background. Your DNS service provider or an add-on seems to be resolving firefox as a valid host name instead of showing an error -- which is what you would normally expect.

What happens if you go to http://firefox/ -- do you get a service provider or add-on results page? If so, does the page indicate the culprit in this scenario or provide an opt-out option? Often there will be a link for more information in the header or footer parts of the page.

I searched http://firefox/ in the address bar and I got an error http://i.imgur.com/e0BgVtd.png

Judging from the AT&T Logo and the dnserrorassist.att.net address, I have a pretty good idea who's behind this. Try the links below the Yahoo logo that say "Why did I get this page?" and "Opt-out of this Service" to see whether you can get rid of the unwanted feature.