Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.cpp	(revision 59820)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/seamless/UIMachineWindowSeamless.cpp	(revision 59821)
@@ -313,5 +313,6 @@
         UIMachineWindow::setMask(m_maskFull);
         /* Update viewport region finally: */
-        m_pMachineView->viewport()->update(toUpdate);
+        if (m_pMachineView)
+            m_pMachineView->viewport()->update(toUpdate);
     }
 }