I am having the same issue when I go to:
http://mywebsite.com/?paypalListener=paypal_standard_IPN
I get the following message:
PayPal IPN Request Failure
My only payment gateway is PayPal, I haven't done any modifications to woocommerce, and from what I can tell, I am not getting a notification back from PayPal that the customer has paid, so instant downloads are not available from my website, which I need.
I am running WP 3.5 and am running framework 5.5.3, and woocommerce 1.6.6