I just purchased the $4.99 iPhone app. I had it last year on my Droid and it worked awesome. But...after I purchased I went to watch one of the practice videos and it just turns the screen black and I cannot get it to do anything else. I am very new with this IPhone and am not impressed at this point. So if anyone has any suggestions let me know. I can't even figure out how to "shut down" right now.