Ok, looks like the SEF URLs were messing with it. However, the website doesn't seem to be receiving the payment notifications. I've tried setting the PayPal verify URL to both www.paypal.com & www.paypal.com with neither working.

The current PayPal IPN settings are still set to my old website:
www.myoldwebsite.com /administrator/components/com_virtuemart/notify.php
Do I need to change it to something else?

PayPal sends this notification URL with purchases made in my new website though:
www.mynewwebsite.com/index.php ?option=com_vmeticket &task=paypal.receivePayment&order_id=9

Dear,

It's hard to say where should be the problem. We'll check it. Could you send me link to your page and FTP access to Diese E-Mail-Adresse ist gegen Spambots geschützt! Du musst JavaScript aktivieren, damit Du sie sehen kannst.