Products disappearing from from carts

I’ve been using this plug-in for a couple of months and at first I thought it was the answer to my prayers. I make one-of-a-kind products and have had the good fortune to have them be in high demand. The link above is devoid of products now. About once every 3 or 4 weeks I do a “drop” in which I upload about 50 products and then people start hitting the site. I get 5000 to 10000 hits in a short period of time. So the cart timer, with its message about a product being in somebody’s cart, is just what I needed.

The only problem is that every drop I get about 10 instances of people having a product in their cart but getting a message that they can’t checkout now because that item is no longer available. Sometimes if they wait it resolves itself. Usually, if they take it out, hoping to put it back in again, it will get snapped up by somebody else. So there’s lots of frustration and anxiety.

I’m afraid it’s very hard to reproduce the error because it happens under high-traffic circumstances but it happens on every drop.

Any pointers or advice much welcome.

-Jim

The page I need help with: [log in to see the link]