I've found with ID CS (3.0.1), with large files, that when attempting to do an export to PDF, ID will "flatten" all the pages (in my case 24), appear to finish, but ID CS crashes back to the finder. If I use the print to PDF command instead, I have no problems at all.
Not sure why this is happening, but I'm posting in case others have seen a smiliar issue or have a solution.
Best,
Peter