Sometimes applications on iPhone or iPod touch close unexpectedly because the device is running low on application memory (please note that this is not the same as storage memory or "Capacity" show on iTunes when you synchronize your device).
In most instances, restarting your iPhone or iPod touch will fix the issue. To do this, press and hold the Sleep button on top of the device for a few seconds until a red slider appears, and then slide the slider. Wait a few seconds, and the press and hold the Sleep button again until the Apple logo appears.
If you are still experiencing problems after restarting your iPhone or iPod touch, please create a new support ticket describing your problem.