JQuery :: Script For Show / Hide Slickbox Not Working In IE6

The following script works in all web browsers fine, just not IE6. It also has to work in IE6 so ignoring it isn't an option. Javascript is below:

<SCRIPT START>
$(document).ready(function() {
// hides the slickbox as soon as the DOM is ready
$('#div1').hide();
$('#close').hide();
// shows the slickbox on clicking the noted link
$('#open').click(function() {
$('#div1').fadeIn('slow');
$('#close').fadeIn();
$('#open').fadeOut();
return false;
});
// hides the slickbox on clicking the noted link
$('#close').click(function() {
$('#div1').fadeOut('fast');
$('#close').fadeOut();
$('#open').fadeIn();
return false;
});

// toggles the slickbox on clicking the noted link
$('#slick-toggle').click(function() {
$('#div1').toggle(400);
return false;
});
document.getElementById("loading").className = "loading-visible";
var hideDiv = function(){document.getElementById("loading").className = "loading-invisible";};
var oldLoad = window.onload;
var newLoad = oldLoad ? function(){hideDiv.call(this);oldLoad.call(this);} : hideDiv;
window.onload = newLoad;
});
<SCRIPT END>