I'm working with a student who reports that when he downloaded Reader for Mac, he couldn't read the pdf files I created (with animations and sound produced via Presenter). He is using Reader X, but when I asked what he had listed in the "About Adobe Plug-Ins" list, he said there was nothing there. I suspect that's why he's not able to read the newer PDf files. But does anyone have a suggestion on why the download didn't have any plugins, or questions at least some questions I can ask him to try to pin down the problem. He reports that his system is running OSX Snow Leopard.
The first thing I would ask is if he's absolutely positively sure that he is actually using Reader to open the files. By default, Mac Preview opens PDF files on a Mac.
If you haven't already, have him open Adobe Reader then use File>Open to open the PDF and see what happens.
If that doesn't work, let us know if there are any error messages...etc.