function childMenu(el,state){

  for(var n=0; n<el.childNodes.length; n++){
    if( el.childNodes[n].nodeName.toLowerCase()=="ul" ){
      el.childNodes[n].style.display = state;
    }
  }

}

function parseMenu(el){

  el = document.getElementById("menu");

  for( var n=0; n<el.getElementsByTagName("li").length; n++ ){

    el.getElementsByTagName("li")[n].onmouseover=function(){
      childMenu(this,"block");
    }

    el.getElementsByTagName("li")[n].onmouseout=function(){
      childMenu(this,"none");
    }

  }

}