Strange LayoutManager error when loading external swf

Question

The swf loads and I get no popup errors in the browser.  But in debug mode my FlexBuilder console reads:
[SWF] C:\~projects\source\flexbuilder\tests\dyvetntive_moderator_test\bin-debug\assets\swf\pres entation.swf - 1,592,516 bytes after decompression
undefined
    at mx.managers::LayoutManager/doPhasedInstantiation()[C:\autobuild\3.2.0\frameworks\projects \framework\src\mx\managers\LayoutManager.as:668]
    at Function/http://adobe.com/AS3/2006/builtin::apply()
    at mx.core::UIComponent/callLaterDispatcher2()[C:\autobuild\3.2.0\frameworks\projects\framew ork\src\mx\core\UIComponent.as:8628]
    at mx.core::UIComponent/callLaterDispatcher()[C:\autobuild\3.2.0\frameworks\projects\framewo rk\src\mx\core\UIComponent.as:8568]
Loading other swf's produces the same result.
What is that?

Answer 1

Turns out it's probably a bug:
http://bugs.adobe.com/jira/browse/FB-24339
Third party vendor wrote:
We have researched this issue. It's not an issue of ours. The crash happens when the loaded AS2 Movie uses _quality property of the MovieClip object.
Step 1 to reproduce the issue.
Create a simples AS2 file with Adobe Flash Studio which has the only line:
this._quality = "BEST"
and publish this Flash file into "QualityBug.swf" file.
Compile the following application with Flex. As you can see there is no code of ours at all:
Code:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" initialize="onInit()">
   <mx:Script>
      <![CDATA[
         import mx.core.UIComponent;
         import flash.display.Loader;
         import flash.net.URLRequest;
         private function onInit():void
            var loader:Loader = new Loader;
            var container:UIComponent = new UIComponent();
            container.addChild(loader);
            this.addChild(container);
            var request:URLRequest = new URLRequest("QualityBug.swf");
            loader.load(request);
      ]]>
   </mx:Script>
</mx:Application>
Launch this application in debug mode. The same crash. This means that issue is related to Adobe product family.
We will try to report to Adobe about this issue.
Since the issue happens only when debugging on IE we may recommend using other web browser for these purposes, for example Firefox until Adobe fix the problem with their product.