Creating a pdf from Word with changing page size and orientation

I have a 150 page Word 2010 document, mostly in A4 portrait, but there are a number of pages in A3 Landscape dotted within it.

When I convert to pdf, it crashes and fails to generate the document.

What can I do about this to have Acrobat Pro X correctly generate the document with the specified page size and orientations.

[update]

I can now add an update to this post.

I discovered that the document was originally created and saved in Word 2002 format.  Every time I used the Create PDF function, it crashed the word file and produced a repaired file.

So I then saved the repaired file in docx format, and tried again, and it correctly created the pdf without crashing.

No further comments required, problem solved.