Made some changes to tpl_shopping_cart_default.php and either because of those changes or just coincidentally, now when adding anything to the cart the page errors out with "The connection was reset / The connection to the server was reset while the page was loading."

Even more strange is when you hit the back button, it shows the item in the cart with a quantity ranging from 4-10. You can go to the shipping cart and see item with various quantities there.

So, something it happening at the moment the add to cart button is clicked. Any ideas what?