Sounds like you're going to have to "break" it to play it. You may want to check with Disney on this one before you do, as they may have some information regarding this. They may be able to explain why it won't play in your ZUNE software. Sadly, most of the "Digital Content" you get from DVDs becomes locked to your computer, and unplayable in the iTunes or ZUNE systems. It's rediculous, IMO, but that's how they play the game.
Try checking into ripping the DVD directly using ripper software and then load it into the ZUNE device.
That...or your ZUNE decided to get a sense of taste.

Just kidding, I'm just sick of the crap that Disney puts out these days. Sick sick siiiiiiiiiick.