The cogwheel or gear is the result of insufficient memory on your device. This can usually be resolved by force-closing the app.

To "Force Close" any app on an iOS device:
1. From the Home screen, tap the Home button twice.
2. Swipe up on the App you wish to close

To “Force Close” any app on an Android device:
1. Open the Main Menu of your device
2. Select Settings
3. Select Apps or Manage Applications
4. Find the App you wish to close in the list of applications
5. Select the App

If you can't get this to work properly, you can try restarting your device and then running the app.