diff -r fe978d063cc5 src/simulator/default-simulator-impl.cc
--- a/src/simulator/default-simulator-impl.cc	Tue Jan 06 15:28:03 2009 +0100
+++ b/src/simulator/default-simulator-impl.cc	Tue Jan 06 15:38:24 2009 +0100
@@ -144,7 +144,7 @@
 void
 DefaultSimulatorImpl::Run (void)
 {
-
+  m_stop = false;
   while (!m_events->IsEmpty () && !m_stop) 
     {
       ProcessOneEvent ();
diff -r fe978d063cc5 src/simulator/realtime-simulator-impl.cc
--- a/src/simulator/realtime-simulator-impl.cc	Tue Jan 06 15:28:03 2009 +0100
+++ b/src/simulator/realtime-simulator-impl.cc	Tue Jan 06 15:38:24 2009 +0100
@@ -421,6 +421,7 @@
   NS_ASSERT_MSG (m_running == false, 
                  "RealtimeSimulatorImpl::Run(): Simulator already running");
 
+  m_stop = false;
   m_running = true;
   m_synchronizer->SetOrigin (m_currentTs);