var interval_time = 6000; // 3 seconds between changes
var item_count;
var item_interval;
var old_item = 0;
var current_item = 0;

$(document).ready(function() {
    item_count = $(".promoAdItem").size();

    $(".promoAdItem").each(function(i) {
        $(this).hide();
    });
    $(".promoAdItem:eq(" + current_item + ")").fadeIn("slow");
    if (item_count > 1) {
        item_interval = setInterval(item_rotate, interval_time); // time in milliseconds
        $('#promoAdContainer').hover(function() {
            clearInterval(item_interval);
        }, function() {
            item_interval = setInterval(item_rotate, interval_time); //time in milliseconds
            item_rotate();
        });
    }
});

function item_rotate() {
    current_item = (old_item + 1) % item_count;
    $(".promoAdItem:eq(" + old_item + ")").fadeOut("slow", function() {
        $(".promoAdItem:eq(" + current_item + ")").fadeIn("slow");
    });
    old_item = current_item;
}