HELP! Bookmarking is taking forever

I create 300 - 500 page manuals (Windows XP using Word 2003 documents) with chapter numbering/pictures/graphics ranging in file size from 6MB to 30MB
 
Everything has been working OK and time to PDF is usually about 5 - 10 minutes depending on file size
 
Tried to PDF a 6MB file and the computer with Acrobat 9pro (CS4) now takes 1 hour to create bookmarks and and another hour to create the PDF. A few weeks ago it would have taken about 6 minutes. I have added no new software.
 
Same file on another computer with Acrobat version 7 takes only 5 minutes with the same settings on Windows XP
 
The "enable accessibility" is turned off, lots of virtual memory and settings are similar
 
I re-installed Acrobat 9pro, loaded the Acrobat updates and checked the windows settings but no change in performance.
 
The Acrobat 9pro computer is constantly repaginating while creating the bookmarks but the Acrobat 7 computer does it immediately
 
Even if the Acrobat 9pro computer doesn't convert the word heading styles or have to bookmark, the Acrobat 7 computer is still faster even while doing the heading conversion.
 
Anyone have a similar problem or can suggest a solution.
 
Any suggestions would be appreciated