Index: /trunk/src/VBox/Main/src-client/SessionImpl.cpp
===================================================================
--- /trunk/src/VBox/Main/src-client/SessionImpl.cpp	(revision 56448)
+++ /trunk/src/VBox/Main/src-client/SessionImpl.cpp	(revision 56449)
@@ -1140,4 +1140,6 @@
         pLockW->release();
 
+        Assert(!pLockW->isWriteLockOnCurrentThread());
+
         LogFlowThisFunc(("Calling mControl->OnSessionEnd()...\n"));
         HRESULT rc = mControl->OnSessionEnd(this, progress.asOutParam());