Custom Fields Yield Errors upon Addition to Cart

[armana]

Upon adding a product to the cart that has custom fields, VM displays several errors. It says the product is successfully added, then gives:

Error the quantity of the product for calculation is 0, please notify the shopowner, the product id 0

Below this, in the cart attributes area, several notices (undefined indexes) appear from default_pricelist.php (lines 147,163, 165, 171). This is only for products with attributes.
VM: 2.0.8
Joomla: 1.5.25
Perhaps it is also worth noting that I receive these notifications before the cart page loads: http://i.imgur.com/JArka.png

Thanks in advance