MarketPress Confirm Payment Error: "There was a problem finalizing your purchase. Line item 1 i

There is a problem when trying to purchase the following item in live credit card mode only. Manual payment gateway works just fine.

https://excelfamilyhealth.com/store/products/trancor-gaba-glutamate-balance-formula/

After you add it to your shopping cart, go through the purchaser and payment information gathering process, and click "Confirm Payment", This error comes up, for this product only.

We populated the products by importing hundreds of products, and we fear that this isn't an isolated incident.

Any suggestions on what we should look for?