function randomImage(objID) {
	
	var randomNumber = Math.floor(Math.random()*3);
document.getElementById('headerRotate').style['background'].url='Images/header_rotate" +randomNumber +".jpg)';
	/*document.getElementById(objID).style.background-image = "background-image:url(background-image:url(Images/header_rotate" +randomNumber +".jpg);"*/
	alert("please stop " +document.getElementById('headerRotate').style['background'].url)
}