I get around 30 minutes into a movie and it freezes. By checking all the downloaded chapters I can see they're all there to the end of the movie but I can't get further that 30 minutes in, then blackness. This the situation on the iPad and iTunes viewed on the laptop. Any ideas....do I have to re download. Have tried a reboot of the iPad. should I just wait to see if it unfreezes....like I say all the chapters seem to be there.