diff --git a/CMakeExternals/OpenCV.cmake b/CMakeExternals/OpenCV.cmake
index 244903fa1f..8cb94f9681 100644
--- a/CMakeExternals/OpenCV.cmake
+++ b/CMakeExternals/OpenCV.cmake
@@ -1,64 +1,65 @@
 #-----------------------------------------------------------------------------
 # OpenCV
 #-----------------------------------------------------------------------------
 
 if(MITK_USE_OpenCV)
 
   # Sanity checks
   if(DEFINED OpenCV_DIR AND NOT EXISTS ${OpenCV_DIR})
     message(FATAL_ERROR "OpenCV_DIR variable is defined but corresponds to non-existing directory")
   endif()
 
   set(proj OpenCV)
   set(proj_DEPENDENCIES)
   set(OpenCV_DEPENDS ${proj})
 
   if(NOT DEFINED OpenCV_DIR)
 
     set(additional_cmake_args )
     if(MITK_USE_Python)
       list(APPEND additional_cmake_args
            -DBUILD_NEW_PYTHON_SUPPORT:BOOL=ON
           )
     endif()
     
     # 12-05-02, muellerm, added QT usage by OpenCV if QT is used in MITK
+    # 12-09-11, muellerm, removed automatic usage again, since this will struggle with the MITK Qt application object
     if(MITK_USE_QT)
       list(APPEND additional_cmake_args
-           -DWITH_QT:BOOL=ON
+           -DWITH_QT:BOOL=OFF
            -DWITH_QT_OPENGL:BOOL=OFF
            -DQT_QMAKE_EXECUTABLE:FILEPATH=${QT_QMAKE_EXECUTABLE}
           )
     endif()     
 
     set(opencv_url ${MITK_THIRDPARTY_DOWNLOAD_PREFIX_URL}/OpenCV-2.4.2.tar.bz2)
     set(opencv_url_md5 d5d13c4a65dc96cdfaad54767e428215)
 
     ExternalProject_Add(${proj}
       SOURCE_DIR ${CMAKE_BINARY_DIR}/${proj}-src
       BINARY_DIR ${proj}-build
       PREFIX ${proj}-cmake
       URL ${opencv_url}
       URL_MD5 ${opencv_url_md5}
       INSTALL_COMMAND ""
       CMAKE_GENERATOR ${gen}
       CMAKE_ARGS
         ${ep_common_args}
         -DBUILD_DOCS:BOOL=OFF
         -DBUILD_TESTS:BOOL=OFF
         -DBUILD_EXAMPLES:BOOL=OFF
         -DBUILD_DOXYGEN_DOCS:BOOL=OFF
         -DWITH_CUDA:BOOL=ON
         ${additional_cmake_args}
       DEPENDS ${proj_DEPENDENCIES}
     )
 
     set(OpenCV_DIR ${CMAKE_CURRENT_BINARY_DIR}/${proj}-build)
 
   else()
 
     mitkMacroEmptyExternalProject(${proj} "${proj_DEPENDENCIES}")
 
   endif()
 
 endif()
diff --git a/Modules/QmitkExt/QmitkPropertyObservers/QmitkStringPropertyEditor.cpp b/Modules/QmitkExt/QmitkPropertyObservers/QmitkStringPropertyEditor.cpp
index e1dfa35e96..754c075f60 100644
--- a/Modules/QmitkExt/QmitkPropertyObservers/QmitkStringPropertyEditor.cpp
+++ b/Modules/QmitkExt/QmitkPropertyObservers/QmitkStringPropertyEditor.cpp
@@ -1,52 +1,55 @@
 /*===================================================================
 
 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 "QmitkStringPropertyEditor.h"
 
 QmitkStringPropertyEditor::QmitkStringPropertyEditor( mitk::StringProperty* property, QWidget* parent )
 : QLineEdit( parent ),
   PropertyEditor( property ),
   m_StringProperty(property)
 {
   PropertyChanged();
   connect(this, SIGNAL(textChanged(const QString&)), this, SLOT(onTextChanged(const QString&)));
 }
 
 QmitkStringPropertyEditor::~QmitkStringPropertyEditor()
 {
 }
 
 void QmitkStringPropertyEditor::PropertyChanged()
 {
   if ( m_Property )
     setText( m_StringProperty->GetValue() );
 }
 
 void QmitkStringPropertyEditor::PropertyRemoved()
 {
   m_Property = NULL;
   m_StringProperty = NULL;
   setText("n/a");
 }
 
 void QmitkStringPropertyEditor::onTextChanged(const QString& text)
 {
+  if( m_StringProperty == 0 )
+    return;
+
   BeginModifyProperty();  // deregister from events
   
   m_StringProperty->SetValue(text.toStdString());
   
   EndModifyProperty();  // again register for events
 }