iBooks not loading random pages of textbook

I recently downloaded a PDF file of a textbook. It works great, except for the fact that random pages don't properly show. Does anyone know if I can fix this? I know the page is there because I can zoom in and pieces of the page will show, and others disappear, but it still wont show enough for me to be able to really read the page. I have opened the book on both my Macbook and iPad, same issue on same pages for both.