FrameMaker 11 - Error in PDF Generation

Hi,

I'm working on FrameMaker 11 for a book having more than 500 pages (Unstructured FM).

But when I try to generate PDF of the book, it displays the following error message:

If I click on OK or close the error message, it asks to close the FrameMaker immediately as it has a problem.

Can anyone help me to overcome this issue? Which kind of error it is?

I tried to send a help request on fmerror@adobe.com (provided in error message), but I've not got any response yet.

Thanks in advance.

Dipali.