Hi Tim,
This message is likely coming from PayFlow Pro directly. Although I did not find this specific error message when I searched through PayFlow Pro documentation, my guess would probably be a setting (restriction) on your PayFlow Pro Manager account, or possibly a setting on their account.
In addition, when your Swedish users got these messages, did the transaction fail? Or did they get the message but the payment went through anyway and they got a successful registration?
Thanks,
Candace