I've been having this problem for awhile now. If I type a word while using firefox (in a form, searching a page for that word/phrase, etc.), Firefox will later (at a seemingly random time) do an automatic search for that word/phrase and redirect me to some site (e.g. if I search a page for 'history', Firefox will at a random time, redirect me to, for example, history.com). I have no idea what might be causing this, and it is really annoying when I'm filling out a form online and Firefox randomly goes to some site, interrupting what I was doing at the time.