This document class avoids some initialization problems I've encountered in IE when Flash is loaded from cache

AvoidIECacheProblems.as

package {

  import flash.display.MovieClip;
  import flash.events.Event;

  /**
   * Sometimes, when the SWF is pulled from cache, the first frame is
   * is played before the Flash player is actually initialized. Many
   * functions do not yet exist at this point. In addition, stage.stageWidth
   * is zero. Within a few milliseconds everything is ready.
   */
  public class AvoidIECacheProblems extends MovieClip {
  
    public function AvoidIECacheProblems() {
      this.addEventListener(Event.ENTER_FRAME, onFirstFrame, false, 0, true);
    }

    private function onFirstFrame(event:Event):void {
      if (this.stage.stageWidth) {
        this.removeEventListener(Event.ENTER_FRAME, onFirstFrame, false);
        this.initialize();
      }
    }

    protected function initialize():void {
      // this is where the magic happens
    }
  }
}