orders randomly not going through

[amy purple]

I'm getting orders regularly on my site through both paypal and using credit cards. However, I had three customers contact me to say that they placed orders in early december and were wondering when they'd receive them. One was on the 4th, one the 9th and i forget when the other was. From talking to the customers, i found out that they all used a cc (via authorize.net), none of them received an order confirmation and all of them fully completed the order to the checkout_success page. The stock was not removed from my site and i didn't receive any e-mails about the orders (since apparently, they didn't exist according to osc). It is just randomly that these orders weren't going through. I'm not sure why this might be happening. Any help would be greatly appreciated. I contact a guy who usually helps me out with any contribs that i can't do myself and he felt it was related to my web hosting. I've since changed hosts (not related to this issue) but it's only been a few weeks, so I can't be certain if it's still happening or not. thanks...amy