[jQuery] ready and jquery 1.2.3

I'm seeing more and more evidence that the ready function isn't really
working properly with jquery 1.2.3 and FF 2.
$(function(){
$('#mydiv').hide();
});
things like above, when the page loads sometimes i see the div, then
it disappears.
Is there just a problem with the shortcut? Is it a combination with
1.2.3 and FF?
I didn't notice this happening before with 1.2.2.