diff --git a/shell/model/homemodel.py b/shell/model/homemodel.py
index 9d7d68cb..598562b8 100644
--- a/shell/model/homemodel.py
+++ b/shell/model/homemodel.py
@@ -110,7 +110,7 @@ class HomeModel(gobject.GObject):
                 self._current_activity = act
             else:
                 self._current_activity = None
-                logging.error('Actiivty for window %d was not yet launched.' % xid)
+                logging.error('Activity for window %d was not yet launched.' % xid)
         else:
             self._current_activity = None
             logging.error('Model for window %d does not exist.' % xid)
diff --git a/shell/view/Shell.py b/shell/view/Shell.py
index 3f0ef8fe..b8678ddb 100644
--- a/shell/view/Shell.py
+++ b/shell/view/Shell.py
@@ -14,6 +14,7 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
+from sets import Set
 import logging
 
 import gobject
@@ -32,6 +33,7 @@ class Shell(gobject.GObject):
     def __init__(self, model):
         gobject.GObject.__init__(self)
 
+        self._activities_starting = Set()
         self._model = model
         self._hosts = {}
         self._screen = wnck.screen_get_default()
@@ -60,8 +62,12 @@ class Shell(gobject.GObject):
     def _activity_added_cb(self, home_model, home_activity):
         activity_host = ActivityHost(home_activity)
         self._hosts[activity_host.get_xid()] = activity_host
+        if home_activity.get_type() in self._activities_starting:
+            self._activities_starting.remove(home_activity.get_type())
 
     def _activity_removed_cb(self, home_model, home_activity):
+        if home_activity.get_type() in self._activities_starting:
+            self._activities_starting.remove(home_activity.get_type())
         if not home_activity.get_launched():
             return
         xid = home_activity.get_xid()
@@ -127,8 +133,14 @@ class Shell(gobject.GObject):
         home_model.notify_activity_launch_failed(handler.get_activity_id())
 
     def start_activity(self, activity_type):
+        if activity_type in self._activities_starting:
+            logging.debug("This activity is still launching.")
+            return
+
         logging.debug('Shell.start_activity')
 
+        self._activities_starting.add(activity_type)
+
         handler = activityfactory.create(activity_type)
 
         home_model = self._model.get_home()