while(true){
aleatorio = Math.random();
numero = Math.round(aleatorio * 5);

if (numero == 0){
imagen = "http://img59.imageshack.us/img59/6955/headertony.png";
break;}

if (numero == 1){
imagen = "http://img195.imageshack.us/img195/742/headerloki.png";
break;}

if (numero == 2){
imagen = "http://img705.imageshack.us/img705/4557/leenaheader.png";
break;}

}
document.write('<a href="https://magical-times.forenverzeichnis.com/" target="_self" ><img src="' + imagen + '" border=2 style="width: 800px; height: 400px"></a>');