function rndlogo(){
  i = Math.floor(Math.random()*4);
  switch (i) {
   case 1:
      logoimage = '/images/mixi/logo04_kamina.jpg';
   break;
   case 2:
      logoimage = '/images/mixi/logo05_buta.jpg';
   break;
   case 3:
      logoimage = '/images/mixi/logo06_yoko.jpg';
   break;
   default:
      logoimage = '/images/mixi/logo07_simon.jpg';
   break;
  }
}