A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Reader X then ... that should be good enough for now.
It's possible that there's something in the JPGs that's giving PPT indigestion (and it's passing that along to the PDF).
Can you post an example slide or two someplace where we can download it?
Skydrive for example?
And/or as a test, if you still have the original JPG files, convert them to BMP.
Delete the pics from PPT and re-add them, using the BMP filies this time.
Convert that to PDF and see if the problem still arises.