I ran a presentation and now I get a message of ‘App is not responding’, why is that?

The DROID ZX Player is a low end device and should be treated as such. If you overload your presentation the CPU will be too busy to respond to the OS broadcast messages and Controller pings and the ANR (Android not responding) message will remain on the screen indefinitely, until the device is power cycled. It is recommended you build a clean presentation and test your content to make sure it plays nice with the DROID ZX Player.