e-commerce paypal ipn

Hello - I'm doing a project that will only be selling a couple of files, but we want the process to be tight, so I want to use the e-Commerce module and PayPal to auto-create user accounts upon purchase so they can login upon return from PayPal.

I'm working with Drupal 5.5 and E-Commerce 5.x-3.4. I've set my PayPal IPN URL properly because I can see the ipn hit in the logs. What I see each time I test are the following 2 errors:

Type php
User Anonymous
Location [domain.com]/paypal/ipn