android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@42b4efa8 is not valid; is your activity running?

[alexlittle]

android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@42b4efa8 is not valid; is your activity running?
at android.view.ViewRootImpl.setView(ViewRootImpl.java:712)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:356)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:234)
at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:153)
at android.view.Window$LocalWindowManager.addView(Window.java:559)
at android.app.Dialog.show(Dialog.java:277)
at openwave.nurhi.mobile.learning.utils.UIUtils.showAlert(UIUtils.java:110)
at openwave.nurhi.mobile.learning.adapter.DownloadModuleListAdapter.installComplete(DownloadModuleListAdapter.java:169)
at openwave.nurhi.mobile.learning.task.InstallDownloadedModulesTask.onPostExecute(InstallDownloadedModulesTask.java:180)
at openwave.nurhi.mobile.learning.task.InstallDownloadedModulesTask.onPostExecute(InstallDownloadedModulesTask.java:1)
at android.os.AsyncTask.finish(AsyncTask.java:631)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4935)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
at dalvik.system.NativeStart.main(Native Method)

[alexlittle]

Happens if video download is started but then user reorientates screen and.or leaves activity