You probably have Find As You Type enabled? http://kb.mozillazine.org/Accessibility.typeaheadfind http://kb.mozillazine.org/Accessibility.typeaheadfind It's pr

You probably have Find As You Type enabled? http://kb.mozillazine.org/Accessibility.typeaheadfind http://kb.mozillazine.org/Accessibility.typeaheadfind It's probably pretty rare nowadays, since it's off by default and rather hidden in the settings dialog ("Search for text when you start typing"). I had it activated up until (quite) a few years ago, and I think I switched it off, because of bad JavaScript interactions.