I was having the same problem as this guy above. I did as you suggested and now my page has a 404 after I hit the submit order button. The 404 looks like this:
"The requested URL /churchlife/OS1A was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Apache/2.0.64 (Unix) mod_ssl/2.0.64 OpenSSL/0.9.7a mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/220.127.116.1135 Server at www.churchliferesources.org Port 80"
OS1A is the product ID for the first product in the cart. I am wondering if the two got mixed up, and how on earth that would happen.
Jason, I'm almost there - don't give up on me...