I'm a newbe. My web designer set me up with the latest version of Zen Cart and it's worked fine until now. Two days ago, a customer ordered an item from my store and Zen Cart did not register that an item had been purchased from the catalog. There was no decrease in the number of items in stock. The only way I could tell that a purchase had been made was that I received a PayPal e-mail of a transaction.

How do I best troubleshoot this issue?

If this isn't the right place to post this question, please let me know where to do so. Thanks!