Every once and a while with Lego Pirates the wii puts out a high pitch noise and the screen freezes up. I have to un plug the wii to get it to reset.
Is it just Lego PotC? How long's it been happening? How old is your Wii
In my experience, the Wii freezing in how you've described (it's happened to me a few times) is an internal error of sorts, characterized by the console being unresponsive to any and all input. Could be a problem with the game itself, be it the disc is improperly made, or scratched. On the contrary, the Wii could be malfunctioning from age, or it isn't programmed as good as it should be.