opac = 0;
function opacIn() {
	var obj = document.getElementById('ad').style; 
    if(opac != 100){
        opac+=2;
        setOpac(obj, opac);
        setTimeout('opacIn()', 10);
    }else{
        setTimeout('opacOut()', 10000);
    }
}
function opacOut() {
	var obj = document.getElementById('ad').style; 
    if(opac > 0){
        opac-=1;
        setOpac(obj, opac);
        setTimeout('opacOut()', 30);
    }
}

function setOpac(object, opacity) {
    object.opacity = (opacity / 100);
    object.MozOpacity = (opacity / 100);
    object.KhtmlOpacity = (opacity / 100);
    object.filter = "alpha(opacity=" + opacity + ")";
}