The playlist loads every time in FF but only the first time in IE (6-8), after that only randomly. If I alert the error that's thrown I get "TypeError: playerReady is undefined".

My code looks good and obviously works since FF displays the playlist perfectly. I've got no idea how to solve this. Anyone?

<script type='text/javascript'>
        var so = new SWFObject('/UI/Flash/player.swf', 'ply', '<%=FlashWidth %>', '<%=FlashHeight %>', '9', '#ffffff'),
            playlistURL = '<%=PlaylistURL %>',
            imageURL = '<%=GetBackgroundImageUrl() %>';
            so.addParam('allowfullscreen', 'true');
            so.addParam('allowscriptaccess', 'always');
        if (playlistURL !== '') {
            so.addVariable('playlistfile', playlistURL);
            so.addVariable('playlist', 'none');
            so.addVariable('enablejs', 'true');
        }
        else {
            so.addVariable('file', '<%=FlashURL %>');
        }   

        if (imageURL.length > 0) {
         so.addVariable('image', imageURL);
        }
        so.write('preview<%=PlayerID %>');
    </script>