Ohh ..... wonder if something's corrupted.
Is the rest of the book readable?
For some reason or another I had to convert a book I bought in the epub format to mobi before I could read it on the Playbook.
And yet, in it's original epub format each page showed and read perfectly in Calibre and Sony Reader for PC.
Don't know why the Playbook had trouble with it .... but I worked around it by changing the format to Mobi in Calibre and then side loading again.