Program received signal SIGKILL exception comes up when I quit in the multitasking bar (iPhone)

When I double tap the home button and quit out of my app from the multitasking bar and open the app again, Xcode reads: "Thread 1: program received signal: SIGKILL" and freezes my iPod. The app has 1500+ lines so I can't really put any code up, sorry. What could I be doing wrong?