Hi Community,
Thanks for helping to bring this to our attention. We have just finished up the database work we've been doing that should resolve this problem, so the Auctiva Checkout system should no longer be error prone as described in this thread.
We apologize for any inconveniences this issue has caused. If you have any additional questions or concerns, please feel free to contact our customer support team using the web form on the following page: http://www.auctiva.com/help/requesthelp.aspx
-Mike