当我第二次导航到嵌套片段时应用程序崩溃

我正在使用嵌套片段，片段加载得很好。但是当我在此框架布局中加载另一个片段并想要再次加载嵌套片段时，我的应用程序崩溃了。

07-14 16:58:21.272: E/AndroidRuntime(1813): java.lang.IllegalStateException: Activity has been destroyed
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1342)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:595)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:574)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at me.kaidul.uhunt.Fragment1.onCreateView(Fragment1.java:23)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1460)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:911)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444)
07-14 16:58:21.272: E/AndroidRuntime(1813):     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:429)

我的父 Fragment 类：

public class Fragment1 extends SherlockFragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment1, container, false);
        Fragment fragmentC = new HeadlinesFragment();
        Fragment frag = new Child();
        FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
        transaction.add(R.id.child_fragment, fragmentC );
        transaction.add(R.id.child_fragment2, frag );
        transaction.commit();
        return rootView;
    }

}

Edit: 这就是我将所有片段添加到活动中的方法：

FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        // Locate Position
        switch (position) {
        case 0:
            ft.replace(R.id.content_frame, fragment1);
            break;
        case 1:
            ft.replace(R.id.content_frame, fragment2);
            break;
        case 2:
            ft.replace(R.id.content_frame, fragment3);
            break;
        }
        ft.commit();

这与嵌套片段的已知错误有关。这是解决这个问题的一种方法 -https://stackoverflow.com/a/15656428/574785 https://stackoverflow.com/a/15656428/574785