I have solved the problem with the page only half loading by updating to the PHP5 Beta worldpay code.
Now I have another problem! I can checkout and process the card - I have tried this using my own credit card on a live environment. Worldpay process the card just fine (I can see it in my Worldpay transaction list on the worldpay site).
However, Zen Cart doesn't create the order - IE: There are no orders on the system and if I log back in again as a customer the products are still showing in my shopping cart.
Any help please please please :)
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