Hmm... I don't know. If there was that large of a cart problem, to the point where that many people can't put more than one item in at a time. I would think you'd hear about it. Especially with the volume you seem to be doing. I could see it being tied to some sort of free shipping deal, or other type of sale... where you have people purposely buying more stuff to meet the criteria somehow. I would think that if anything... people would just cancel their order altogether if they couldn't get the cart to work right. I mean, assuming that you sell stuff that can be purchased elsewhere. That's what I would do if that happen to me. But if I really wanted your stuff and there was an issue, I'd contact the site. I have to think multiple people would, if it was that wide scale a problem. I wouldn't rule out a fluke. There's some really weird patterns that just seem to happen with people in sales.