Acrobat can't find PDF when when diagnosed by Flightcheck

When i put a PDF through Markzware's Flightcheck, Acrobat is supposed to open the PDF automatically after Flightcheck runs its analysis. But instead, I get an error message saying "There was an error opening this document. This file cannot be found." The PDF is on my desktop. I ran this by Markzware and sent them a PDF to try. They were unable to duplicate the problem on their end; the PDF opens just fine for them. They suggested Adobe be contacted. It doesn't matter which PDF or its location, I get the same message every time. Does anyone have any ideas? Thanks.