diff --git a/Plugins/org.mitk.gui.qt.application/src/internal/org_mitk_gui_qt_application_Activator.cpp b/Plugins/org.mitk.gui.qt.application/src/internal/org_mitk_gui_qt_application_Activator.cpp
index 7a0ca2427a..b9b06decb9 100644
--- a/Plugins/org.mitk.gui.qt.application/src/internal/org_mitk_gui_qt_application_Activator.cpp
+++ b/Plugins/org.mitk.gui.qt.application/src/internal/org_mitk_gui_qt_application_Activator.cpp
@@ -1,71 +1,73 @@
 /*===================================================================
 
  The Medical Imaging Interaction Toolkit (MITK)
 
  Copyright (c) German Cancer Research Center,
  Division of Medical and Biological Informatics.
  All rights reserved.
 
  This software is distributed WITHOUT ANY WARRANTY; without
  even the implied warranty of MERCHANTABILITY or FITNESS FOR
  A PARTICULAR PURPOSE.
 
  See LICENSE.txt or http://www.mitk.org for details.
 
  ===================================================================*/
 
 #include "org_mitk_gui_qt_application_Activator.h"
 
 #include "QmitkGeneralPreferencePage.h"
 #include "QmitkEditorsPreferencePage.h"
 
 #include <QmitkRegisterClasses.h>
 
 #include <QtPlugin>
 
 namespace mitk
 {
 
   org_mitk_gui_qt_application_Activator* org_mitk_gui_qt_application_Activator::m_Instance = 0;
   ctkPluginContext* org_mitk_gui_qt_application_Activator::m_Context = 0;
 
   void org_mitk_gui_qt_application_Activator::start(ctkPluginContext* context)
   {
     this->m_Instance = this;
     this->m_Context = context;
 
     BERRY_REGISTER_EXTENSION_CLASS(QmitkGeneralPreferencePage, context)
     BERRY_REGISTER_EXTENSION_CLASS(QmitkEditorsPreferencePage, context)
 
     QmitkRegisterClasses();
 
     this->m_PrefServiceTracker.reset(new ctkServiceTracker<berry::IPreferencesService*>(context));
     this->m_PrefServiceTracker->open();
   }
 
   void org_mitk_gui_qt_application_Activator::stop(ctkPluginContext* context)
   {
     Q_UNUSED(context)
 
+    this->m_PrefServiceTracker.reset();
+
     this->m_Context = 0;
     this->m_Instance = 0;
   }
 
   ctkPluginContext* org_mitk_gui_qt_application_Activator::GetContext()
   {
     return m_Context;
   }
 
   org_mitk_gui_qt_application_Activator *org_mitk_gui_qt_application_Activator::GetInstance()
   {
     return m_Instance;
   }
 
   berry::IPreferencesService::Pointer org_mitk_gui_qt_application_Activator::GetPreferencesService()
   {
     return berry::IPreferencesService::Pointer(m_PrefServiceTracker->getService());
   }
 
 }
 
 Q_EXPORT_PLUGIN2(org_mitk_gui_qt_application, mitk::org_mitk_gui_qt_application_Activator)
diff --git a/Plugins/org.mitk.gui.qt.common/src/internal/QmitkCommonActivator.cpp b/Plugins/org.mitk.gui.qt.common/src/internal/QmitkCommonActivator.cpp
index 97a5037d01..404d31559c 100644
--- a/Plugins/org.mitk.gui.qt.common/src/internal/QmitkCommonActivator.cpp
+++ b/Plugins/org.mitk.gui.qt.common/src/internal/QmitkCommonActivator.cpp
@@ -1,70 +1,72 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #include "QmitkCommonActivator.h"
 
 #include <berryPlatformUI.h>
 #include <mitkLogMacros.h>
 
 QmitkCommonActivator* QmitkCommonActivator::m_Instance = 0;
 ctkPluginContext* QmitkCommonActivator::m_Context = 0;
 
 ctkPluginContext* QmitkCommonActivator::GetContext()
 {
   return m_Context;
 }
 
 QmitkCommonActivator* QmitkCommonActivator::GetInstance()
 {
   return m_Instance;
 }
 
 berry::IPreferencesService::Pointer QmitkCommonActivator::GetPreferencesService()
 {
   return berry::IPreferencesService::Pointer(m_PrefServiceTracker->getService());
 }
 
 void
 QmitkCommonActivator::start(ctkPluginContext* context)
 {
   this->m_Instance = this;
   this->m_Context = context;
   this->m_PrefServiceTracker.reset(new ctkServiceTracker<berry::IPreferencesService*>(context));
 
   if(berry::PlatformUI::IsWorkbenchRunning())
   {
     m_ViewCoordinator = QmitkViewCoordinator::Pointer(new QmitkViewCoordinator);
     m_ViewCoordinator->Start();
   }
   else
   {
     MITK_ERROR << "BlueBerry Workbench not running!";
   }
 }
 
 void
 QmitkCommonActivator::stop(ctkPluginContext* context)
 {
   Q_UNUSED(context)
 
   m_ViewCoordinator->Stop();
   m_ViewCoordinator = 0;
 
+  this->m_PrefServiceTracker.reset();
+
   this->m_Context = 0;
   this->m_Instance = 0;
 }
 
 Q_EXPORT_PLUGIN2(org_mitk_gui_qt_common, QmitkCommonActivator)