1.5.1

If you're on Mac OS X 10.1.5 (ed. 10.1.5, not 10.5.1, heh), using Mozilla 1.5, and crashing whenever you attempt to download something just isn't your idea of a good browsing experience, then you should rush right out and get Mozilla 1.5.1. This is a Mac-only release and is really only worth upgrading from Mozilla 1.5 if you're running OS X 10.1.x. Users of 10.2 and 10.3 need not update from Mozilla 1.5.