From your stacktrace, it is not related to the size of the project.
Can you open a bug in JIRA with the stacktrace, please?
You have somewhere in your code base, a MXML file which leads to this exception. It would great if you could try to identify this one.
You would then be able to add to the test suite to avoid regressions.
now I know where to start looking I'm positive i can track this one down for yo9u this evening.
i'll get back to you later
Great Glenn !