Index: /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumItem.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumItem.cpp	(revision 78391)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumItem.cpp	(revision 78392)
@@ -232,15 +232,15 @@
     /* Attempt to change medium type: */
     comMedium.SetType(enmNewType);
-
+    bool fSuccess = true;
     /* Show error message if necessary: */
     if (!comMedium.isOk() && parentTree())
     {
         msgCenter().cannotChangeMediumType(comMedium, enmOldType, enmNewType, treeWidget());
-        return false;
+        fSuccess = false;
     }
     /* Reattach the medium to all the vms it was previously attached: */
     foreach (const AttachmentCache &attachmentCache, attachmentCacheList)
         attachTo(attachmentCache);
-    return true;
+    return fSuccess;
 }
 
Index: /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumManager.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumManager.cpp	(revision 78391)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/medium/UIMediumManager.cpp	(revision 78392)
@@ -273,7 +273,5 @@
     if (   comMedium.isOk()
         && newData.m_options.m_enmMediumType != oldData.m_options.m_enmMediumType)
-    {
         pMediumItem->changeMediumType(oldData.m_options.m_enmMediumType, newData.m_options.m_enmMediumType);
-    }
 
     /* Try to assign new medium location: */
@@ -1046,5 +1044,5 @@
     {
         m_pDetailsWidget->setData(pMediumItem ? *pMediumItem : UIDataMedium(type));
-        if (pMediumItem)
+        if (pMediumItem && currentMediumItem())
             m_pDetailsWidget->enableDisableMediumModificationWidgets(currentMediumItem()->isMediumModifiable());
     }