slide show for ios and android crash

Hi All,

     i have create a app for ios and android. it will load some image dynamically from local directory and show on screen. but i realize after few hour the app will automatically crash. please help. code below is my code

timer = new Timer(AppSetting.SCREENSAVER_INTERVAL * 1000);

                timer.addEventListener(TimerEvent.TIMER, loadNewImage);

                timer.start();

private function loadNewImage(e:TimerEvent):void {

                            //timer.

            //timer.removeEventListener(TimerEvent.TIMER, loadNewImage);

            //var f_Index:int = int(Math.random() * images.length);

            var f_Loader:Loader =  new Loader();

            f_Loader.contentLoaderInfo.addEventListener(Event.COMPLETE, function(e:Event):void {

                //trace(System.totalMemory / 1024);

                f_Loader.contentLoaderInfo.removeEventListener(Event.COMPLETE, arguments.callee);

                f_Loader = null;

                if (screensaver) {

                    removeChild(screensaver);

                    screensaver.bitmapData.dispose();

                    screensaver = null;

                    //System.gc();

                }

                screensaver = Bitmap(f_Loader.content);

                addChild(screensaver);

                screensaver.width = AppSetting.STAGE.stageWidth;

                screensaver.height = AppSetting.STAGE.stageHeight;

            });

            f_Loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, function(e:IOErrorEvent):void {

                trace("load screensavers image error!");

            },false);

            try {

                f_Loader.load(new URLRequest(File.applicationStorageDirectory.resolvePath(AppSetting.SCREENSAVER_PATH + images[f_Index]).url));

                f_Index = f_Index + 1;

                if (f_Index == images.length)

                {

                    f_Index = 0;

                }

            } catch (e:Error) {

                trace("load screensavers image error!");

            }

            //timer.addEventListener(TimerEvent.TIMER, loadNewImage);

            //trace(System.totalMemory / 1024);

            dispatchEvent(new Event(LOADED));

        }

i have set all var to null but it still crash.