Getting PayPal error #10413 when multiple purchases made of the same item.

Hi, since yesterday I have had a number of people receiving the following PayPal error message when trying to check out.
"There was a problem connecting to PayPal to setup your purchase. Please try again.

10413 - Transaction refused because of an invalid argument. See additional error messages for details. - The totals of the cart item amounts do not match order amounts."

This is only happening when someone is choosing to purchase more than 1 of the SAME item.

Can you look into this please and let me know how to fix it as soon as possible as I have had quite a few people complaining about not being able to check out.

Thank You.
Linda