Swf exports without Document class second time around

So, this is a weird one. I have a Flash 10, AS3, CS5 project with a document class. When i open up CS5 fresh and test it, it exports just fine and works as it should. Upon trying to export it again it looks like it fails to run the document class (trace in constructor is absent) and the stage remains as it would before any code modifies it. If i close Flash and reopen everything again, it will export once, then fail to do so all subsequent times.

Suffice to say, I’m mystified. Is there some possible setting that could be causing this? Has anyone encountered anything remotely similar?

Any help or insight would be greatly appreciated.