Rom Help!?!?

I downloaded a game 4 my sister (Kirbys Dream Land 3) and she played it and when she got to the first real boss (Whispy) she killed it and then got on the star but every time it goes to the next world on the mini map type thing (were kirby is a little pink dot) it freezes right before it goes to the next world. anyine know what is going on???? Or how to fix it???? "If your not dead, That just means I haven't found you yet..."