Index: /trunk/src/VBox/Frontends/VirtualBox/src/globals/UIActionPool.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/globals/UIActionPool.cpp	(revision 57879)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/globals/UIActionPool.cpp	(revision 57880)
@@ -112,5 +112,5 @@
 UIMenu* UIAction::menu() const
 {
-    return qobject_cast<UIMenu*>(QAction::menu());
+    return QAction::menu() ? qobject_cast<UIMenu*>(QAction::menu()) : 0;
 }
 
@@ -959,7 +959,9 @@
 {
     /* Make sure menu is valid: */
+    AssertPtrReturnVoid(sender());
     UIMenu *pMenu = qobject_cast<UIMenu*>(sender());
     AssertPtrReturnVoid(pMenu);
     /* Make sure action is valid: */
+    AssertPtrReturnVoid(pMenu->menuAction());
     UIAction *pAction = qobject_cast<UIAction*>(pMenu->menuAction());
     AssertPtrReturnVoid(pAction);
Index: /trunk/src/VBox/Frontends/VirtualBox/src/widgets/UIPopupStack.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/widgets/UIPopupStack.cpp	(revision 57879)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/widgets/UIPopupStack.cpp	(revision 57880)
@@ -314,9 +314,12 @@
 {
     /* Menu-bar can exist only on QMainWindow sub-class: */
-    if (QMainWindow *pMainWindow = qobject_cast<QMainWindow*>(pParent))
-    {
-        /* Search for existing menu-bar child: */
-        if (QMenuBar *pMenuBar = pMainWindow->findChild<QMenuBar*>())
-            return pMenuBar->height();
+    if (pParent)
+    {
+        if (QMainWindow *pMainWindow = qobject_cast<QMainWindow*>(pParent))
+        {
+            /* Search for existing menu-bar child: */
+            if (QMenuBar *pMenuBar = pMainWindow->findChild<QMenuBar*>())
+                return pMenuBar->height();
+        }
     }
     /* Zero by default: */
@@ -328,9 +331,12 @@
 {
     /* Status-bar can exist only on QMainWindow sub-class: */
-    if (QMainWindow *pMainWindow = qobject_cast<QMainWindow*>(pParent))
-    {
-        /* Search for existing status-bar child: */
-        if (QStatusBar *pStatusBar = pMainWindow->findChild<QStatusBar*>())
-            return pStatusBar->height();
+    if (pParent)
+    {
+        if (QMainWindow *pMainWindow = qobject_cast<QMainWindow*>(pParent))
+        {
+            /* Search for existing status-bar child: */
+            if (QStatusBar *pStatusBar = pMainWindow->findChild<QStatusBar*>())
+                return pStatusBar->height();
+        }
     }
     /* Zero by default: */