Calling shmemBase_closeConnection() closes the Handles opened/created for the mutexes used to serialize reads and writes for each stream of the connection. After this call, the Handle id that used to identified a previously closed mutex could be recycled by the OS and assigned to a new object. If a thread tries to read or write a packet after the connection was closed the call will end up in sysIPMutexEnter() which calls WaitForMultipleObjects() on the previously closed mutex and the shutdown event. If the Handle id was indeed recycled that call will affect the state of the new object.