I have an Options box that hovers in the top right of the webpage. It\'s opacity is set to 10% so as not to be obstructive to users. When they hover over (mouseenter) it I
Call stop to terminate any existing animations before starting a new one. You should also probably use hover instead of mouseenter/mouseleave.
$("#dropdown").hover(function() {
$(this).stop().fadeTo('fast',1);
$("#options").stop().slideDown();
}, function() {
$(this).stop().fadeTo('fast',0.1);
$("#options").stop().slideUp();
});