Insert from File puts an Adobe ad in my document

I'm on a deadline to get a document out tonight.  The document consists of 6 pages.  The first two were brought in by my scanner and saved as PDF.  Then I opened that document and used Tools | Insert from File to add 4 existing 1-page PDF documents to the end of my first document.  This seemed to go okay until I reviewed the resulting PDF document.  In place of page #3 is an ad for Adobe Acrobat/Reader.  There is a big logo and then the text,

For the best experience, open this PDF portfolio in Acrobat X or Adobe Reader X, or later."

When I try to delete the page, the original page does not show up.  When I re-insert the page, I get the ad.  If I re-insert at a different location in the document, I get the ad.  I've never had this happen before.  What is going on and how can I get rid of it?

Thanks,

Dave

Acrobat 10.1.8