Menu won't slide up (sometimes)

Menu won't slide up (sometimes)

 Hey guys,

I've followed this tutorial: http://www.noupe.com/tutorial/drop-down-menu-jquery-css.html

I adapted it to make it so the menu slides down when you put your mouse over, instead of clicking it.
I also integrated "hoverIntent" to it.

I am having problems with it though.

If you visit my website at: www.roxbourne.com

Sometimes the services menu won't slide back up and gets stuck. I don't understand how something can be so intermittent.






Here is the Jquery:

jQuery(document).ready(function(){

    jQuery("ul.subnav").parent().append("<span></span>"); //Only shows drop down trigger when js is enabled - Adds empty span tag after ul.subnav
   
    jQuery("ul.topnav li.drop").mouseover(function() { //When trigger is clicked...

        //Following events are applied to the subnav itself (moving subnav up and down)
        jQuery(this).parent().find("ul.subnav").slideDown('slow').show(); //Drop down the subnav on click

        jQuery(this).parent().hoverIntent(function() {
        }, function(){   
            jQuery(this).parent().find("ul.subnav").stop().slideUp('slow'); //When the mouse hovers out of the subnav, move it back up
        });
       
                //Following events are applied to the trigger (Hover events for the trigger) 
         }).hoverIntent(function() { 
             jQuery(this).addClass("subhover"); //On hover over, add class "subhover" 
         }, function(){  //On Hover Out 
             jQuery(this).removeClass("subhover"); //On hover out, remove class "subhover"

});

});

I'd be very grateful if anyone could help. Thanks in advance.