Index: /trunk/src/VBox/Frontends/VirtualBox/src/settings/machine/UIMachineSettingsStorage.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/settings/machine/UIMachineSettingsStorage.cpp	(revision 76204)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/settings/machine/UIMachineSettingsStorage.cpp	(revision 76205)
@@ -3843,5 +3843,5 @@
     }
 
-    if (!fCancelled)
+    if (!fCancelled && !uMediumId.isNull())
     {
         m_pModelStorage->addAttachment(QUuid(m_pModelStorage->data(index, StorageModel::R_ItemId).toString()), enmDevice, uMediumId);