I am having the same problem as this person was on this thread:
http://www.zen-cart.com/showthread.p...multiple-times

Our settings are correct:
Check stock level true
Subtract stock true
Allow Checkout false
Mark product out of stock ***
Products status in Catalog when out of stock should be set to 0

And yet it still allows people to checkout with more items than are available, it then sets the products quantity to -1. We have had to refund 2 orders now and not sure what is causing this to happen.

Payment Modules In Use:
Authorize net aim

Shipping Modules In Use:
Ceon Advanced Shipper
Fedex Web Services

Other Modules In Use:
Sitemap XML
Google Analytics

Have searched forums all day and cannot find a solution - any help would be appreciated.

Site is winez2u.com