Safari has been quitting unexpectedly a lot on my eMac 1.25 OS X Tiger lately. I've also had some "freezes" - or never ending turning beach ball - if I try to load too much at once.
I've installed all software updates, but I can't remember if the problem did occur after one of these....
Coming back to this, since updating to 10.5.2 some flash content crashes Safari, and other stuff doesn't, but for the most part my browser stops responding.
I've had to force quit Safari 10+ times today, something in that update serious screwed it all up.