event

The addedToStage event fires when a component becomes part of the display list. The display list is rooted in the Stage component and contains all of its descendants. When your component is on the Stage it participates in the standard render loop and the event dispatching loop.

Keep in mind that even though your component is not in the display list, it can still be asked to render itself using the draw method of BitmapData.

The removedFromStage event is dispatched to a component when it is removed from its parent. If the parent component was on the display list of the Stage, then the removedFromStage event will be dispatched to the component along with the removed event.

The removed event is fired when a component is removed from its current parent. This is accomplished with the removeChild(child:DisplayObject) method (or removeChildAt(index:int)).

If the component was previously on the Stage, then the removedFromStage event will also be dispatched to the component.

The added event is fired when a component is added as a child to another component. This is accomplished through the addChild(child:DisplayObject) method (or addChildAt(child:DisplayObject,pos:int)).

When the component is removed, it will receive the removed event. This is the complementary event to added.

Flash dispatches certain standard events based on the interactions of components, especially with regards to rendering and the display list. Generally, a component receives added and addedToStage, then render events. When the component is removed it will usually receive removed and removedFromStage. Obviously, if the component is only added to another component, and the parent component is not yet on the Stage, then the "Stage" events won't fire until the topmost parent is added to the Stage.

Problem

You have a handler attached to the removedFromStage event on your component and this handler is being called unexpectedly. Sometimes called during component initialization and sometimes during resizing.