Hello Margaret,
This is all news to us, and unfortunately we cannot address things we don't know about.
Perhaps we could start by having you send us a System Snapshot (from Help | System Status choose Snapshot from the button in the top left hand corner of the dialog and email it to us).
It would also be useful to know what exact version of PO you are running, and whether the data passes the Data Integrity Check.
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Andrew Bates