iTunes will play some movies but not all.

I wanted to watch my copy of Avengers. I had bought the BluRay combo pack which gives me a code to download the movie. I put it on my laptop the day I got it. I've watched it twice on itunes, as well as The Lion King and Up. Now I'm trying to watch it but when I click on it, nothing happens. The top bar which tells you the information about whatever you are watching/listening to shows Avengers/ Joss Weaton, and says I'm 14 seconds into the movie out of 2 hours and 22 minutes.. but nothing happens. The screen does not change, no sound comes out, the bar doesn't move. It just sits there. I clicked on The Lion King, and it works. It picked up right where I left off last time I started watching it. Suggestions?

FYI: I am using Windows 7 and I have the current iTunes- I do believe.