Issue with The Dark Knight Blu-ray disc: Changing Aspect Ratios + Sound

[boredomHD]

I don't know if this issue has been posted before, but I did a search and I couldn't really find anything. When I play the Dark Knight on bedroom Blu-ray Player (Magnavox NB530MGX) the picture constantly changes from full screen to widescreen depending on the scene. This is the first movie that has done this to me, and I have watched over 50 discs on my player so far. Is this something with the coding of the movie? I've tried altering my television settings to full screen 100% of the time, but when I do this little parts of the movie are cut off. They are not cut off when the movie changes by itself. Why does the movie keep changing?

BTW: I have a 32" Sanyo DP32648 720p. It has not changed the picture size with any other movie. I do not think this is an issue with my television.