I would like to thank you for all of your help resolving my problem. It was my PayPal configuration on PayPal, not QuickSell that was causing me problems.
On PayPal, under Profile/My Selling Tools/Block Payments/Block payments from U.S. users who do not provide a Confirmed Address:
You must select "No", other wise the IPN comes back from PayPal as pending and that is why I was getting the endless loop. Once I selected NO the extension started working.
Thanks for all of the help.