How to debug a runtime stack underflow error?

Question

I'm really struggling to resolve a stack underflow that I'm getting.  The traceback I get at runtime is:
VerifyError: Error #1024: Stack underflow occurred.
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at flash.net::URLLoader/onComplete()
This is particularly difficult to debug because when I run in debug mode it does not happen at all.  It only happens when compiled as a release.
Does anyone have any tips on how to debug a Stack Underflow?  Are have a clean explanation of what that means for Flash?
In case it helps, this error is occurring when I click a button whose handler makes an RPC call, which uses a URLLoader, an AsyncToken, and then invokes the set of AsyncResponder instances associated with the AsyncToken.  With some server-side logging as well as some logging hacked into the swf, I know that the UrlLoader is successfully doing and GET'ing a crossdomain.xml file, is correctly processing it (if I wreck it, I get a security error), and is also successfully completing the "load" request (the server sends the data)... the underflow seems to be happening in the Event.COMPLETE listening/handling process (as is, of course, implied by the traceback as well).
mxmlc used = from flex_sdk_4.5.0.20967
Example player (I've tried a few) = 10.2.153.1

Answer 1

Peter Blazejewicz wrote:
crossposted:
http://stackoverflow.com/questions/6270837/how-to-debug-a-runtime-stac k-underflow-error
Yes... I intended to say so here but didn't get to it yet.  View traffic was extremely low here and I thought I'd see how stackoverflow compared.  I tend to check there first for most languages usually, but thought I'd try here as well to see if I should break that habit.
As per the SO post, my specific problem was resolved by switching my variable initialization routine from the "initialize" application event, to the onCompletion event.  Although I am obviously "happy" about this since this issue cost me a lot of time and hair, it does not really indicate how I would go about debugging such an internal error in the future, so the question is technically unanswered.
As to the question from Flex harUI, I am compiling indirectly via the MXMLC in the SDK, through the Amethyst Visual Studio plugin (which I'm auditioning).  The only libraries involved are from the flex_sdk_4.5.0.20967 SDK.  The project is quite small (a test project), consisting only of 1 MXML file and 2x .AS files.