var max_image=12;
var imageCounter=1;
var timer;

function imageChange(i) {
                imageCounter++;
                i.src="logo"+imageCounter+".png";
                if (imageCounter==max_image) imageCounter=0;
}

function imageRandom() {
                timer = setTimeout("imageRandom()", 1000 * 60);
                var Li = document.getElementById('logoImage');
                var random = Math.floor(Math.random()*max_image) + 1;
                Li.src="logo"+random+".png";
                imageCounter = random;
}