Index: /trunk/src/VBox/Frontends/VBoxHeadless/VBoxHeadless.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VBoxHeadless/VBoxHeadless.cpp	(revision 31022)
+++ /trunk/src/VBox/Frontends/VBoxHeadless/VBoxHeadless.cpp	(revision 31023)
@@ -819,4 +819,14 @@
                 break;
         }
+        else
+        {
+            /* Use the GUID. */
+            rc = virtualBox->GetMachine(id, m.asOutParam());
+            if (FAILED(rc))
+            {
+                LogError("Invalid machine uid!\n", rc);
+                break;
+            }
+        }
 
         Log(("VBoxHeadless: Opening a session with machine (id={%s})...\n",