Huge Problem with oversized image

Hi everybody, I have to create a credits scroll (like in the movies in flash) for that I got a nice list of about 300 lines :cantlook:
Now everything is typed in and the looks pretty nice, BUT when I animate to go from the bottom border to the top border, I get some freaky stuff like this:

Everything is mixed up, and the bottom of my list appears at the top.
Anybody a clue why this is happening?

Here some more informations:
Stagesize: 464x256
Credits (graphic): 506x4401

Thanks for any help! much appreciated