Context: Just to provide some context: I use Flash CS 5.5 for my exporting, so it's possible that the issue you're seeing isn't related. Maybe it is. Anyway, just wanted to let you know.
After doing some searching around the communities, I learned that there was a new Java update for OS X Lion (grab it here). I haven't done any Java installs/updates as of late and thought this may be the reason. I'm not very technical, so I didn't know why this would solve the problem.
But hey, it did solve the problem.
So go download that new update. It may just work for you too!
Related Link: Apple.com - Java for OS X Lion Page
Related Link: Apple.com - Support Forums for this Issue