Thank you for your post.
From your screen shot, I see it is processing page 3 when the error occurs. How large is the form? Is it 3 pages long? If only one page in length, what occurs when you omit the third record?
Are you able to print to PDF on any other layout? If you select a different record and print to PDF (current record only), does it work?
Any other information you can provide may be helpful.