I'm trying to help out a friend with his Magento site - Magento ver. 220.127.116.11. When customers try to checkout, the form works correctly through the 1. Checkout Method; 2. Billing Information; and 3. Shipping Information. Unfortunately, on the 4. Shipping Method tab, when you click the Continue button it gives you the message "Loading Next Step..." but it will not advance to the 5. Payment Information tab. It simply restores the Continue button, stays on the 4. Shipping Method tab, and the customer can't ever complete the purchase. The problem is occurring across all major browsers, and apparently just started recently. The site owner told me he hasn't made any changes on the back end. Help! Thanks in advance.