document.onmouseover=check_menu
  
  function check_menu()
  {
   if(last_nav!='')
   {nav_off(last_nav,last_menu);}   
  }
  var detected_browser=navigator.appName;
  var btype='ie';

  //if(detected_browser!='Microsoft Internet Explorer')
  //{btype='ns';}

  var last_menu='';
  var last_nav='';
  
  function nav_on(nav,menu)
  {
   if(document.images[nav])
   {
    document.images[nav].src='images/nav/on/'+menu+'_on.gif';
    if(last_menu != "" && last_menu!= menu){nav_off(last_nav,last_menu);}
    if(btype == 'ie')
    {document.all[menu].style.visibility='visible';}
    else
    {document[menu].visibility='show';}	
    last_menu=menu;
	last_nav=nav;
   }  
  }
  
  function nav_off(nav, menu)
  {
   if(document.images[nav])
   {
    document.images[nav].src='images/nav/off/'+menu+'.gif';
	if(btype == 'ie')
    {document.all[menu].style.visibility='hidden';}
    else
    {document[menu].visibility='hidden';}	   
   }  
  }