We would need to see the file to determine the cause/workaround and fix - it sounds like it's a specific element within that file causing the crash. If you're able to link to the file or determine steps to reproduce (or the specific element of the file causing the problem and paste that into a FLA you can share), we can certainly look into it.
I'm putting the file up on our website for you to grab.
Please treat this file confidentially.
Point your web browser to http://www.torpexgames.com/adobeflashcs4 where the username is "addeden" and the password is "cs4bluetop".
We included the fonts we're using, too.
425 644 4263
Oops, sorry, I thought you were from Adobe. Sorry, when dealing with strangers on the Internet we'd have to have some sort of verified NDA in place when sending stuff based on an unannounced title.
Yes, I am from Adobe ("Employee" next to user name at left is assigned only to folks at the company).
You can email me at jdh (at) adobe or through PM with a new login and I can look at the file if you want me to.