I realize this is a very old thread, but I am having the same problem, it just loops back to the shopping cart after confirming the order. I think that the template files are in the wrong place, but if I remove them from "default" and move them to the "classic" folder (which is the template being used), there's no option for google checkout at all....the radio button disappears, and there Ive never seen the big Google CheckOut button everyone has mentioned at all. I've tried every solution I've seen, and nothing works. Does anyone have any NEW ideas? Any help is appreciated.