Updating code for CS3?

Basically i made a game about a year ago on FlashMX (flash player 6) and now im using CS3 and would like to involve some of its new features (filters etc.)
This requires my game to flash player 8/9. When i set this flash times for about 20 seconds when i test movie then says
“a script in this movie is causing flash player to run slowly. if it continues to run, your computer may become unresponsive. do you want to abort the script?”
So im guessing a part of my code is not recognised by flash player 8 but i really have no idea.
I was wondering if someone could take a look at the code and tell me what might be causing the problem?

http://www.csvid.com/maxoys/files/fighting_game_kirupa.fla

The main actions are on:
first and second frames (actions layer)
the spaceship (middle)
the enemy plane (right of screen)
and the three moving backgrounds

Thanks a lot :slight_smile:

max