The animation don't work again if something was already shown or hidden in Firefox (2.0.4).

the fix for this is to change animation part in fx.js like this:

animate: function( prop, speed, easing, callback ) {

var hidden = jQuery(this).is(":hidden");

for ( var p in prop ) {

if ( prop[p] == "hide" && hidden || prop[p] == "show" && !hidden ) return;

};

return this.queue(function(){

this.curAnim = jQuery.extend({}, prop);

var opt = jQuery.speed(speed, easing, callback);

var self = this;

jQuery.each( prop, function(name, val){

var e = new jQuery.fx( self, opt, name );

if ( val.constructor == Number )

e.custom( e.cur(), val );

else

e[ val == "toggle" ? hidden ? "show" : "hide" : val ]( prop );

});

});

},