Was it saved with a newer profile (Adobe Acrobat 9 or 10)? Try saving it as PDF/A... but do keep in mind that editing a PDF is generally considered bad practice - even more so if you plan to read it on a "cheap Chinese thing".
It could also be a page numbering issue. If page 1 was split into two halves (top and bottom), both of them are probably marked as "Page 1" and the reader somehow gets confused. If it were me, I would probably extract the PDF as a bunch of images, batch process them with Irfanview or something and let the reader display them as-is. Worked with my PSP when I was in collage.
There weren't any dedicated PDF readers for it back then.
PS: Welcome to the forums. Both of you...