problem wirth load() and IE7

problem wirth load() and IE7

Hello,
I have some strange problem with load() in IE7 only. What I'm trying to do is to use load() to get part of php page and load that content into table cell DIV tag, everything works just fine in FF but in IE content is loaded below earlier content. Some code will explain better:
inside if HTML template I have:
  1. <span id="main_content">
  2. <div class="onepage" id="main_div">
  3. <div style="text-align: right; clear: both; margin-right: 30px;">
  4.     <a href="javascript:void(0);" style="color:#000000;font-weight:bold;width:auto"; id="show_all" onclick="javascript: filter_orders('show_all', '1');">Show All</a>
  5.     <a href="javascript:void(0);" style="color:#10E911;font-weight:bold;width:auto;" id="show_complete" onclick="javascript: filter_orders('show_complete', '1');">Complete</a>
  6.     <a href="javascript:void(0);" style="color:#FF6000;font-weight:bold;width:auto;" id="show_processing" onclick="javascript: filter_orders('show_processing', '1');">Processing</a>
  7.     <a href="javascript:void(0);" style="color:red;font-weight:bold;width:auto;" id="show_refunded" onclick="javascript: filter_orders('show_refunded', '1');">Refunded</a>
  8. </div>
  9. <div id="test1">some content</div>
  10. </div>
  11. </span>
.That is example of my filter result page
JS code looks like this:
  1. function filter_orders(filter_id, page)
  2. {
  3.     $("span#main_content").html("&nbsp;");
  4.     $.applyOrdersFilter(filter_id, page);
  5. }
and
  1. jQuery.applyOrdersFilter = function(type, page){
  2.     var filter_type = type;
  3.     var page_num = page;
  4.    
  5.     $("span#main_content")
  6.     .load("/index.php?subdir=customers&pagename=index&action=orders&filter_type="+filter_type+"&page="+page_num+" #main_div")
  7.     .fadeIn("slow");
  8.     return false;
  9. }
so, when I click one of URL's I trigger jquery function and load this same div with different details.
in IE new DIV is added below existing instead of replacing content.
How can I make IE to replace content of DIV instead of adding new DIV below existing?

Regards