G2 Example in PDF Reference Material gives a Damaged File Error

I've been following the example PDF layouts in the free PDF document on how to create PDFs from scratch and I'm having a few problems. I thought the PDFs I had created were the same as the ones outlined in the examples but I keep getting something like "..file was damaged and now repairing.." pop up for a brief second and then disappear. The PDF (just text right now) then comes up looking fine. Can anyone suggest a reason (or reasons) why I might be getting this? I have the example PDF on hand and can e-mail it if anyone can help me out. I would really, really appreciate any help on this. Thanks.

Rob