PDF Document Generation Failure

Whenever PO is being sent across a heirarchy via email, an additional email accompanys the standard PO approval email. In addition the PO approval email does not contain the PDF attached to the PO instead it contains a corrupt file titled 'PO_101_21814_0_US'. The content of the accompanying email is as follows. "The system could not generate and/or communicate at least one of the documents to the supplier or the approver. Please contact the system administrator. ". Please advise. ERP suite version 11.5.10.2 . How do I make the PDF viewable and eliminate that accompanying email? Is there a way to disable it or