diff --git a/Modules/IGT/IGTTrackingDevices/mitkTrackingDevice.cpp b/Modules/IGT/IGTTrackingDevices/mitkTrackingDevice.cpp
index bdf0258c94..1fecec507b 100644
--- a/Modules/IGT/IGTTrackingDevices/mitkTrackingDevice.cpp
+++ b/Modules/IGT/IGTTrackingDevices/mitkTrackingDevice.cpp
@@ -1,93 +1,91 @@
 /*=========================================================================
 
 Program:   Medical Imaging & Interaction Toolkit
 Language:  C++
 Date:      $Date$
 Version:   $Revision$
 
 Copyright (c) German Cancer Research Center, Division of Medical and
 Biological Informatics. All rights reserved.
 See MITKCopyright.txt or http://www.mitk.org/copyright.html for details.
 
 This software is distributed WITHOUT ANY WARRANTY; without even
 the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 PURPOSE.  See the above copyright notices for more information.
 
 =========================================================================*/
 
 #include "mitkTrackingDevice.h"
 #include "mitkTimeStamp.h"
 #include "mitkTrackingTool.h"
 #include <itkMutexLockHolder.h>
 
 typedef itk::MutexLockHolder<itk::FastMutexLock> MutexLockHolder;
 
 
 mitk::TrackingDevice::TrackingDevice() :
   m_Type(TrackingSystemNotSpecified),
   m_State(mitk::TrackingDevice::Setup),
   m_StopTracking(false), m_ErrorMessage("")
 
 {
   m_StopTrackingMutex = itk::FastMutexLock::New();
   m_StateMutex = itk::FastMutexLock::New();
   m_TrackingFinishedMutex = itk::FastMutexLock::New();
   m_TrackingFinishedMutex->Lock();  // execution rights are owned by the application thread at the beginning
 }
 
 
 mitk::TrackingDevice::~TrackingDevice()
 {
-  m_TrackingFinishedMutex = NULL;
-  m_StopTrackingMutex = NULL;
 }
 
 
 mitk::TrackingDevice::TrackingDeviceState mitk::TrackingDevice::GetState() const
 {
   MutexLockHolder lock(*m_StateMutex);
   return m_State;
 }
 
 
 void mitk::TrackingDevice::SetState( TrackingDeviceState state )
 {
   itkDebugMacro("setting  m_State to " << state);
 
   MutexLockHolder lock(*m_StateMutex); // lock and unlock the mutex 
   if (m_State == state)
   { 
     return;
   }
   m_State = state;
   this->Modified();
 }
 
 
 bool mitk::TrackingDevice::StopTracking()
 {
   if (this->GetState() == Tracking) // Only if the object is in the correct state
   {
     m_StopTrackingMutex->Lock();  // m_StopTracking is used by two threads, so we have to ensure correct thread handling
     m_StopTracking = true;
     m_StopTrackingMutex->Unlock();
     //we have to wait here that the other thread recognizes the STOP-command and executes it
     m_TrackingFinishedMutex->Lock();
     mitk::TimeStamp::GetInstance()->Stop(this); // notify realtime clock
     // StopTracking was called, thus the mode should be changed back
     //   to Ready now that the tracking loop has ended.
     this->SetState(Ready);
   }
   return true;
 }
 
 
 mitk::TrackingTool* mitk::TrackingDevice::GetToolByName( std::string name ) const
 {
   unsigned int toolCount = this->GetToolCount();
   for (unsigned int i = 0; i < toolCount; ++i)
     if (name == this->GetTool(i)->GetToolName())
       return this->GetTool(i);
   return NULL;
 }