in the side menu/nested accordion/sidemenu.php page, change the onclick code:
onclick="doHighlighlight(this);updateContant(\'products_results_xml.php?Search=1&ProductCategoryID[]='.$row_SubCategoryList["CategoryID"].'\')"
to:
onclick="window.location=\'products_results.php?Search=1&ProductCategoryID[]='.$row_SubCategoryList["CategoryID"].'\'"