When we send an invoice to QB, by default we do not specify the account receivable associated with it. When this happens QB tries to use the same account that was used on the most recently entered document of the same type. In this case an invoice. The error occurs when an invoice is being posted for a customer with a currency that is different than the account receivable currency from the most recent invoice.
The work around is to specify the account receivable. You can do this by opening the Lists menu, profile lists, sales, terms, and assigning accounts receivable there. Then make sure a term with the correct account is on the ship doc.