You're registering a hashchange
$(window).bind('hashchange', function(){
but you also used #
on your images anchors
<div id="image-1">
<a href="#image-2"><img></a> <!-- HERE'S THE ISSUE -->
</div>
which upon a click will trigger the same event.
so you need to think about your page usability and UI (user interface).
It's not common that a user will click on an image to make a content-slider advance...
One solution would be to rethink about the concept, I would add two nice fancy arrows on both sides of the page - slider.
or you might want to event.preventDefault()
on any click that is triggered on your images
$("#main-content").on("click", "a[href^='image-']", function( event ){
event.preventDefault();
});
hopefully preventing the hashchange
event to trigger. Hope this helped to spot on the issue.
P.S: the menu on the left side is also unintuitive, it's not clear which submenu is opened and which was the parent caller...