Loading Movie in movie-clip problem!

I have a very odd problem.

I have made a movie which consists of 5 buttons. When you click on one of these buttons, they each load a movie into an empty clip on the stage called ‘clips’.
Each of the movies themselves are animations consisting of various scenes. There is a very simple loading bar on the first frame of each.
However, when i preview this project, sometimes the movie clip will remain completely blank until a ‘play’ button is pressed in which case the movie starts. [I forgot to mention there is a small ‘play control’ strip on the main movie for rewinding, stopping etc]… This is very baffling, as if the movie hasn’t actually loaded into ‘clips’. You should at least see the very simple loader bar on the first frame??..
Has anyone encountered this problem before??
Any advice on this would be hugely appreciated. It’s driving me totally mad!! :jail:

thanks

MArll