Game crashes if I press home button on game

This is log cat's logs when game crash time

06-09 11:22:01.482: I/ActivityManager(594): START u0 {act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10200000 cmp=com.android.launcher/com.android.launcher2.Launcher} from pid 594 06-09 11:22:01.602: D/dalvikvm(594): GC_FOR_ALLOC freed 2368K, 29% free 34016K/47460K, paused 102ms, total 102ms 06-09 11:22:01.713: D/dalvikvm(594): GC_FOR_ALLOC freed 587K, 29% free 33982K/47460K, paused 102ms, total 102ms 06-09 11:22:02.223: W/ActivityManager(594): Activity pause timeout for ActivityRecord{427d5658 u0 com.dncgames.kingofdetective/com.unity3d.player.UnityPlayerNativeActivity t55} 06-09 11:22:02.473: I/Unity(27267): onPause 06-09 11:22:02.473: D/Unity(27267): Sensor : Accelerometer ( 1) ; 0.001190 / 0.00s ; MPL Accelerometer / InvenSense 06-09 11:22:02.513: I/Unity(27267): windowFocusChanged: false 06-09 11:22:04.555: I/PowerManagerService(594): Going to sleep by user request... 06-09 11:22:05.176: V/KeyguardHostView(656): Initial transport state: 0, pbstate=0 06-09 11:22:05.196: D/SurfaceFlinger(179): Screen released, type=0 flinger=0xb87ef450 06-09 11:22:05.226: V/KeyguardHostView(656): hide transport, gen:41 06-09 11:22:05.226: V/KeyguardHostView(656): music state changed: 0 06-09 11:22:05.476: D/SurfaceControl(594): Excessive delay in blankDisplay() while turning screen off: 281ms 06-09 11:22:05.596: D/PhoneStatusBar(656): disable: < expand icons alerts ticker system_info BACK* HOME* RECENT* CLOCK* search >

I maked this game by unity with NGUI.

what's the problem & how can I solve it..?