I posted a thread here http://www.zen-cart.com/forum/showthread.php?t=42085 but now I'm having other problems. The reason I installed a new copy of Zen is because checkout was failing. In IE, upon clicking confirm on the last page of the checkout, I get a page cannot be displayed. In Firefox, it wants to download my index.php file. This all started because I enabled the store pickup option, but with it turned off it still does not work. Upon installing 1.3.0.2 with a fresh database, I'm having the same problem. I'm guessing it has to do with Authorize.Net, but maybe someone else has some insight on this problem.