Debugging PDF for error

Debugging PDF for error

I'm creating PDF files using PDFClown java library.
Sometimes, when openning these files with Adobe Acrobat Reader I get the
famous error message:
"An error exists on this page. Acrobat may not display the page correctly.
Please contact the person who created the PDF document to correct the
problem."
The error shows while reading (with Adobe) the attached file only when
scrolling down to the 8'th page, then scrolling back up to 3'td page.
Alternatively, Zooming out to 33.3% will also produce the message.
Just for the record, Foxit reader reads the file flawlessly, as well as
other PDF readers like browsers.
My questions are:
What's wrong with my file?? (file is attached)
How can I find what's wrong with it? is there a tool which tells you where
does the error lie?
Thanks!