timeline delay problem when publish App, exe but not in swf!!!

Hey!!
I totally have no idea what's going on and really need some help. I created a game and everything is done now. My swf is fine, the movie clip that I use to be a background play nice on the scene. But with .app, I realized that there is delay of time that make this movie clip can't finished itself before changing scene. I have tried to resize some bitmaps I'm using but still no hope. And I dont' think it's about the AS2, the code thing, because .swf is fine. So Anyone knows? Where should I check it/ fix it/ or change the setting? Pleaseeeeeeeeeeeeeeeeeeeeeeeeeee

Thanks so much !! =3=

INFO:
I'm using Action Script2
Mac book Pro
this game has 3 scenes; the problem happens in 2nd scene.
I haven't tried exe yet, because I'm using Mac.
It a simple catching and shooting balls game.

If you need more info, let me know.