I cannot really tell exactly how this did happen. Yesterday, I pressed CTRL + C to copy a URL from a web page displayed on Firefox, and it seems I touched something else that wasn't CTRL + C and Firefox loaded a new tab with the home page. Since then just by pressing CTRL Firefox loads the home page.
With 14.04, in Firefox after pressing the Home icon I get the Ubuntu page in the current tab and my home page in a new tab. With 13.10, pressing the Home icon took me directly to my home page. Is this a deliberate change, or a bug?