Debug this application and you'll see "Move indeterminate" traced out every frame:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml" layout="absolute">
<mx:ProgressBar indeterminate="true"/>
</mx:Application>
Regression bug, seems to have been broken in mainline w/ changelist #181937 (9/10/2007)