show dialog with "drop" effect problem in IE6

when i use dialog like this:
$("#dialog").html(msg);
$("#dialog").dialog({
            bgiframe:false,
            modal:true,
            show:"drop",
            hide:"drop",
            width:600,
            minWidth:400,
            minHeight:200
            }).dialog('open');
the "msg" include table html.if the msm include the <select>
element,the whole page will flashing.Have idea?