Image prob while tweening

i have a problem with the final outcome of my tween
i used a mask effect for my image, and it all looks well in the stage
but when i test the movie, the image seems to be movie slightly too, can aniwan tell me the reason?
i have attached the swf for easy reference :beer:
i’m not sure if it’s just me who have this prob, when i view in fullscreen mode, i dun see this problem too, only when in 100% mode
thanx in advance