Strange icon on Firefox heading

I have a strange "icon" that looks like a house showing on my Firefox heading (see snip). When my mouse moves over it shows a web page (http://kurs.ru/index0.html), and when clicked on takes me to a Russian web news site.

I run MSE, SuperAntiSpyware, Mbam and CCleaner every night. I just finished running ESET Online Scanner, Trend HouseCall Scan and MS Safety Scanner. No threats found. I have all updates except IE 10.

How would I get rid of this? Thanks for any help.

sounds like the home button, usually when you click this it takes you to the homepage you have set or the default firefox google search page.
something has changed your homepage. to see this click tools/options in the window that opens look at the general tab and look to see what your homepage is set to.
you can easily change it.
visit the site you usually have set as your homepage,then click the url to highlight it. then drag the highlighted url over to the home button if you do it correctly it will ask you if you want to make this the new homepage or words to that effect.
as to how it changed, not sure maybe you ought to clear your cookies you can look at that in the privacy tab of the options window you just checked the general tab in

boohbah - You were right on the money. I had checked the options tab and had "Show blank page" when Firefox starts but did not notice the next line that had Home Page (which was always blank before).

I'm a HAPPY CAMPER again!

Thanks again for your help.

your welcome. glad to have helped.
i always have google uk as my homepage and i use an addon called new tab homepage ,each time i click the +tab a new page opens with the google uk search page.