Freezes

I have an iPhone 4 and the game sometimes freezes with a black screen. Almost everytime I finish a level actually. So I have to go out of the game and back in. If it didnt so that it would have 5 stars, pretty fun game! Also is this compatible with playing with friends on Facebook? I keep trying to play from the app with people who play on a computer and nothing happens. Now Im stuck and cant get passed level 36. Not paying for the game so I guess Ill have to delete app.

Sjsnxnen about WICKED: The Game, v1.6