This message is zone related ...
Are you sure your database in the configure.php files for:
/includes/configure.php
/admin/includes/configure.php
Match on the database, username and password? YES
You are postive that there is no zone associated with the Payment Module for PayPal IPN ... YES
You have for fun removed and reinstalled and reconfigured the Payment Module for PayPal IPN ... YES installed about 3 times even reloaded and tried again
You have for further giggles and grins closed all browser sessions, cleared your cache and tossed you cookies ...
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