Oscommerce Expert to Fix Paypal Bug

I have a customer who has the PayPal Pro for OScommerce (aka Paypal Direct Payment) installed with Express Checkout enabled. The default currency is in USD. Two Issues Have Now Resulted: 1) If someone places an order with Canadian currency using Paypal, an error is generated when the user is taken back to the oscommerce site from Paypal: An error occured when we tried to process your credit card. Transaction refused because of an invalid argument. See additional error messages for details. (10418) The currencies of the shopping cart amounts must be the same. 2) Customers can no longer purchase Gift certificates (items with GIFT_ in the model number) whether they try to make the purchase with Paypal or with any other payment method in ANY currency.) When they click purchase on the final screen, they are then taken back to the payment screen. The cart has about 15 modifications, but the issue only started happening with the Paypal implementation. Only bid if you have a lot of experience in oscommerce.