function startStoerung(){
    var min = 10000;
    var max = 60000;
    var zufall =  min + parseInt( Math.random() * ( max-min+1 ) )

    window.setTimeout('stoerung()', zufall);
}

function stoerung (){



    var groteskdiv = document.createElement('div');
    groteskdiv.className = 'stoerung';
    groteskdiv.style.display = 'block';
    groteskdiv.id = 'stoerung';
    
    document.getElementById('top').appendChild(groteskdiv);

    window.setTimeout('deleteelement()', 500);
    
    startStoerung();
}

function deleteelement(){

    var stoerung = document.getElementById('stoerung');
    document.getElementById('top').removeChild(stoerung);

}