if (document.images) 
{
   img1 = new Image();
   img2 = new Image();
      img3 = new Image();
   img4 = new Image();
      img5 = new Image();
   img6 = new Image();
   img7 = new Image();
   img8 = new Image();
    img9 = new Image();
   img1.src = "/images/pro_drop4_2b.gif";
   img2.src = "/images/pro_drop4_2a.gif";
      img3.src = "/images/pro_drop4_0b.gif";
   img4.src = "/images/pro_drop4_0a.gif";
      img5.src = "/images/pro_drop4_0b_active.gif";
   img6.src = "/images/pro_drop4_0a_active.gif";
    img7.src = "/images/pro_drop4_2a_active.gif";
     img8.src = "/images/pro_drop4_2b_active.gif";
img9.src = "/images/sub_back.gif";
}