Komisches Phänomen im FireFox

setInterval(function(){ 
	var id = Math.floor(Math.random() * (data.length - 0));
	preLoadImage(id, slideTime - 500);
}, slideTime);

function preLoadImage(id, sTime) {
	var path = data[id]["p"];  
	var file = data[id]["f"];  
	var bild = path + "/" + file;  
	$( document.body ).append( "<div id='img_"+id+"'></div>" )  
	$( "#img_"+id ).css({ "background-image": "url('"+bild+"')" });  
	
	setTimeout(function(){ showImage(id); }, sTime);
}

function showImage(id) {
	var datetime = data[id]["d"];  
	var date = datetime.split(" ");  
	var date = date.split(".");  
	var date = parseInt(date) + ". " + Monat[parseInt(date[1]) -1] + " " + date[2];  
	
	var path = data[id]["p"];  
	var file = data[id]["f"];  
	var width = data[id]["w"];  
	var height = data[id]["h"];  
	
	var bild = path + "/" + file;  
	$( "#dia" ).css({ "background-image": "url('"+bild+"')" });  
	$( "#dia" ).css({ "background-size": "contain" });  
	$( "#date" ).html( date );  
	$( "#date" ).append( "<br>"+width+"x"+height );  
	$( "#date" ).append( "<br>"+file );  
	
	$( "#img_"+id ).remove();  
}