The URLs in the buy links will need to be updated.
http://www.genevaphotoclub.com/wp-content/plugins/easy-paypal-lte/buy.php?wp&id=1&qty=1
will need to become
http://www.genevaphotoclub.com/ezpaypal-ep/buy.php?wp&id=1&qty=1
IOW, replace wp-content/plugins/easy-paypal-lte with ezpaypal-ep in buy links.
This change was necessary for compatibility with some security settings and nginx servers.
I see that you you modified your buy links. Will mark this topic as resolved now.
Just in case any other user lands on this thread looking for the solution, I will repeat it here. In general, the modification needed the buy link URLs is this:
replace wp-content/plugins/easy-paypal-lte/buy.php with ezpaypal-ep/buy.ezp to redirect purchase requests to EZ PayPal endpoint. This now works on nginx servers as well.