We use authorize.net as a payment gateway. They(Authorize) had an outage recently that made it impossible for customers to check out on our website. If someone tried to submit an order during this time, error messages reading "Gateway error: Unable to read response, or response is empty" or "payment capturing error". One customer attempted to place their order 5 or 6 times, with all appearing to fail. However, we looked at our settled transactions report and it looks like one of these orders DID get through and his credit card was processed. Magento has no history of this what so ever. I asked Authorize.net and they claim that their system was back up and running one whole minute before this order came through, so the issue is not with them but with the shopping cart. -_- So, all that being said, how/why would this happen? We have never had this issue before.