IE7 & jQuery-1.6.2: List items being moved down go under the containing elements (multi list sorting)

My code on a fiddle: http://jsfiddle.net/SMqR9/33/

The javascript for quicker reference:

$j = jQuery.noConflict();
$j(function() {

    $j("#sort_content_41,#sort_content_40,#sort_content_42,#sort_content_39").sortable({
        connectWith: '.section-content',
        dropOnEmpty: true,
        zIndex: 1004,
        cursor: 'crosshair'
    });
    $j("#sort_sections").sortable({
        placeholder: "ui-state-highlight",
        connectWith: '.sections',
        axis: 'y',
        zIndex: 1003,
        cursor: 'crosshair'
    });
});

$j(function() {
    $j("section-content").sortable({
        connectWith: "section-content",
        dropOnEmpty: true
    });
    开发者_运维百科$j(".section-content").disableSelection();
});

Now, from a question earlier, someone came up with this code that fixes the z-index thing in IE:

$j('ul').bind('mousedown', function(e) {
    e.stopPropagation();
    if ($j.browser.msie && $j.browser.version < '9.0') $j(this).closest('.section').css('z-index', '5000');
});
if ($j.browser.msie && $j.browser.version < '9.0') {
    $j('ul').bind('mouseup', function(e) {
        $j(this).closest('.section').css('z-index', '1000');
    });
}

which is fine for jQuery 1.3.2 (what I was on previously), but because of IE9, I needed to upgrade to the latest jQuery. When I use the IE < 9 code from above, I can only move the list items once. After that, everything stops. =\ There are no errors / warnings in the webkit inspector. =\

I fixed the problem just be removing the e.stopPropagation();

not sure why it was there in the first place. =\