I am loading a bunch of DisplayObjects and lining them up horizontally by grabbing their .width property and separating each by a certain margin. In doing so, I encountered a bizarre quirk in Flash. Sometimes, Sprites report a massively negative width ( -107373134.4, to be exact ). This occurs when I have attached a DisplayObject that has begun playing a NetStream but has not yet received metaData for the stream (a local .flv). My row gets all confused and places the next object at that massively negative location, which bungles up the rest of the view.
Okay, so the issue was coming from setting the position of the playhead based on the progress of the video before the video had made any progress. Rather than reporting the attempted access of an undefined value, flash decided to try to place the playhead in non-space. While theoretically cool, this prevents practical things from happening. A simple conditional statement fixed things if( video.progress > 0 ) position stuff.