Place this script at very bottom of your page
<script type="text/javascript">
var originalShow = Sys.Extended.UI.ValidatorCalloutBehavior.prototype.show;
Sys.Extended.UI.ValidatorCalloutBehavior.prototype.show = function (force) {
this._elementToValidate.scrollIntoView(false); //true to align with the top of the scroll area
originalShow.call(this, force);
};
</script>