Can you tell us more about how it is set up. There could be a number of reasons why it is not playing. Did you try different browsrs, are you using the console to see what is happening?
What do you need to know about how it is set up?
I'm on a Mac, I've used Safari, Firefox, Chrome and Opera.. doesn't play on any.
I meant - main timeline - symbols - actions, etc.... any code you could post?