Recipient of Excel with embedded PDF can't open PDF object
The embeded object is bundled by COM, the Excel program itself will remember the default program for opening embeded PDF document when user embeds the PDF into Excel file. So if the PDF file is embeded as an Acrobat object, it can not be opened with Power PDF and vice versa, the PDF file embedded as Power PDF object can not be opened with Adobe Reader either.
In this case, you insert the PDF document to Excel when Power PDF is your default, so Excel will remembers to use only Power PDF to open the document. The recipient doesn't have Power PDF, so the error occurs.
If you insert the PDF into Excel using Insert > Object >Package, it does not tag the PDF to force open into the embedding program. In other words, it doesn't care if inserted while the PC had Acrobat or Power PDF, and doesn't care if the reader trying to access it has Power PDF or Acrobat. It opens in any PDF program.