Index: /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumEnumerator.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumEnumerator.cpp	(revision 55983)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumEnumerator.cpp	(revision 55984)
@@ -297,10 +297,11 @@
     /* Check if UIMedium ID was changed: */
     const QString strUIMediumID = uimedium.id();
-    /* UIMedium ID was changed to null string: */
-    if (strUIMediumID.isNull())
+    /* UIMedium ID was changed to nullID: */
+    if (strUIMediumID == UIMedium::nullID())
     {
         /* Delete this medium: */
         m_mediums.remove(strUIMediumKey);
         LogRel(("UIMediumEnumerator: Medium with key={%s} closed and deleted (after enumeration).\n", strUIMediumKey.toAscii().constData()));
+
         /* And notify listener about delete: */
         emit sigMediumDeleted(strUIMediumKey);