var activeImage = 1;
var userSelected = false;
function activateImage(imageNr,random) {
	if (activeImage > 0) {
		Element.toggle('dynImageBox_'+activeImage);
		Element.removeClassName('dynImageLink_'+activeImage,'act');
	}
	Element.toggle('dynImageBox_'+imageNr);
	Element.addClassName('dynImageLink_'+imageNr,'act');
	activeImage = imageNr;
	if (!random) {
		userSelected = true;
	}
}

window.setInterval("changeImage()",4000);

function changeImage() {
	if (!userSelected) {
		activateImage(rand(4), true);
	}
}

function rand ( n ){
  return ( Math.floor ( Math.random ( ) * n +1) );
}