弹出选择框时异常：android.view.WindowLeaked: Activity org.example.sudoku.Sudoku has leake

弹出选择框时错误：android.view.WindowLeaked: Activity org.example.sudoku.Sudoku has leake
小弟今日学习Android，在把书上的例子抄进eclipse的运行的时候发现跳出这个错误，请问有没有人也碰到过呢：
04-12 08:56:49.387: ERROR/WindowManager(706): Activity org.example.sudoku.Sudoku has leaked window [email protected] that was originally added here
04-12 08:56:49.387: ERROR/WindowManager(706): android.view.WindowLeaked: Activity org.example.sudoku.Sudoku has leaked window [email protected] that was originally added here
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.ViewRoot.<init>(ViewRoot.java:227)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.Window$LocalWindowManager.addView(Window.java:424)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.app.Dialog.show(Dialog.java:239)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.app.AlertDialog$Builder.show(AlertDialog.java:802)
04-12 08:56:49.387: ERROR/WindowManager(706): at org.example.sudoku.Sudoku.openNewGameDialog(Sudoku.java:82)
04-12 08:56:49.387: ERROR/WindowManager(706): at org.example.sudoku.Sudoku.onClick(Sudoku.java:44)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.View.performClick(View.java:2364)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.View.onTouchEvent(View.java:4179)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.widget.TextView.onTouchEvent(TextView.java:6532)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.View.dispatchTouchEvent(View.java:3709)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
04-12 08:56:49.387: ERROR/WindowManager(706): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659)
04-12 08:56:49.387: ERROR/WindowManager(706): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.app.Activity.dispatchTouchEvent(Activity.java:2061)
04-12 08:56:49.387: ERROR/WindowManager(706): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.view.ViewRoot.handleMessage(ViewRoot.java:1690)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.os.Handler.dispatchMessage(Handler.java:99)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.os.Looper.loop(Looper.java:123)
04-12 08:56:49.387: ERROR/WindowManager(706): at android.app.ActivityThread.main(ActivityThread.java:4310)
04-12 08:56:49.387: ERROR/WindowManager(706): at java.lang.reflect.Method.invokeNative(Native Method)
04-12 08:56:49.387: ERROR/WindowManager(706): at java.lang.reflect.Method.invoke(Method.java:521)
04-12 08:56:49.387: ERROR/WindowManager(706): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
04-12 08:56:49.387: ERROR/WindowManager(706): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
04-12 08:56:49.387: ERROR/WindowManager(706): at dalvik.system.NativeStart.main(Native Method)