Index: /trunk/src/VBox/Main/src-client/ConsoleImpl.cpp
===================================================================
--- /trunk/src/VBox/Main/src-client/ConsoleImpl.cpp	(revision 51291)
+++ /trunk/src/VBox/Main/src-client/ConsoleImpl.cpp	(revision 51292)
@@ -3784,5 +3784,8 @@
     /* Determine the base path for the device instance. */
     PCFGMNODE pCtlInst;
-    pCtlInst = CFGMR3GetChildF(CFGMR3GetRootU(pUVM), "Devices/%s/%u/", pcszDevice, uInstance);
+    if (strcmp(pcszDevice, "Msd"))
+        pCtlInst = CFGMR3GetChildF(CFGMR3GetRootU(pUVM), "Devices/%s/%u/", pcszDevice, uInstance);
+    else
+        pCtlInst = CFGMR3GetChildF(CFGMR3GetRootU(pUVM), "USB/%s/", pcszDevice, uInstance);
     AssertReturn(pCtlInst, VERR_INTERNAL_ERROR);
 
Index: /trunk/src/VBox/Main/src-client/ConsoleImpl2.cpp
===================================================================
--- /trunk/src/VBox/Main/src-client/ConsoleImpl2.cpp	(revision 51291)
+++ /trunk/src/VBox/Main/src-client/ConsoleImpl2.cpp	(revision 51292)
@@ -3624,5 +3624,8 @@
                     /* Unmount existing media only for floppy and DVD drives. */
                     PPDMIBASE pBase;
-                    rc = PDMR3QueryLun(pUVM, pcszDevice, uInstance, uLUN, &pBase);
+                    if (enmBus == StorageBus_USB)
+                        rc = PDMR3UsbQueryLun(pUVM, pcszDevice, uInstance, uLUN, &pBase);
+                    else
+                        rc = PDMR3QueryLun(pUVM, pcszDevice, uInstance, uLUN, &pBase);
                     if (RT_FAILURE(rc))
                     {