Index: /trunk/src/VBox/Main/MachineImpl.cpp
===================================================================
--- /trunk/src/VBox/Main/MachineImpl.cpp	(revision 35123)
+++ /trunk/src/VBox/Main/MachineImpl.cpp	(revision 35124)
@@ -3399,9 +3399,12 @@
     {
         MediumType_T mtype = medium->getType();
-        if (    mtype == MediumType_MultiAttach
-             || mtype == MediumType_Readonly
-           )
-        {
-            // These two types are new with VirtualBox 4.0 and therefore require settings
+        // MediumType_Readonly is also new, but only applies to DVDs and floppies.
+        // For DVDs it's not written to the config file, so needs no global config
+        // version bump. For floppies it's a new attribute "type", which is ignored
+        // by older VirtualBox version, so needs no global config version bump either.
+        // For hard disks this type is not accepted.
+        if (mtype == MediumType_MultiAttach)
+        {
+            // This type is new with VirtualBox 4.0 and therefore requires settings
             // version 1.11 in the settings backend. Unfortunately it is not enough to do
             // the usual routine in MachineConfigFile::bumpSettingsVersionIfNeeded() for
@@ -3417,5 +3420,5 @@
                )
                 return setError(VBOX_E_INVALID_OBJECT_STATE,
-                                tr("Cannot attach medium '%s': the media types 'MultiAttach' and 'Readonly' can only be attached "
+                                tr("Cannot attach medium '%s': the media type 'MultiAttach' can only be attached "
                                    "to machines that were created with VirtualBox 4.0 or later"),
                                 medium->getLocationFull().c_str());