Help! Lock on Videos in VIDEOS

I downloaded a digital copy of 'Alice In Wonderland' to my iPad several years ago (when both were new). Played fine. I eventually removed it.
I just downloaded "Rise of the Planet of the Apes' by dropping it into iTunes and syncing it to my iPad.
When I opened it the movie is there, but will not play. I can drag the cursor and see the various parts of the movie, hbut that is it.
I noticed a lock symbol in the upper right of the screen. Can't begin to figure out how it got there or how to unlock it.

Is anyone familiar with this issue? I have IOS 5.0 on my iPad. Can this be a feature of 5.0?