If you already used the ActivityGroup class you probably used also the LocalActivityManager instance to manage your group’s activities. I was creating my activity which should also manages its internal history ( using a ViewFlipper for animating the activity views ).
The problem came out once I tried to destroy an activity from the history using the LocalActivityManager destroy method. After an activity was removed from both my internal history and from the local activity manager I was unable to create a new instance of the same activity.
After googling for my problem I found that it was because a bug in the LocalActivityManager class: http://code.google.com/p/android/issues/detail?id=12359
This is exactly my problem! In fact, debugging the android code ( see this post for debugging android code ) at that point it was clear that the record it’s not removed from the internal mActivities map.
Field mActivitiesField = getLocalActivityManager().getClass().getDeclaredField( "mActivities" );
mActivitiesField.setAccessible( true );
((Map) mActivitiesField.get( getLocalActivityManager() )).remove( id );