diff -r 533be42b3c7f src/devices/tap-bridge/tap-bridge.cc
--- a/src/devices/tap-bridge/tap-bridge.cc	Fri Apr 30 13:10:23 2010 -0400
+++ b/src/devices/tap-bridge/tap-bridge.cc	Fri Apr 30 11:03:59 2010 -0700
@@ -233,6 +233,14 @@
   CreateTap ();
 
   //
+  // We're going to spin up a thread soon, so we need to make sure we have
+  // a way to tear down that thread when the simulation stops.  Do this by
+  // scheduling a "destroy time" method to make sure the thread exits before
+  // proceeding.
+  //
+  Simulator::ScheduleDestroy (&TapBridge::StopTapDevice, this);
+
+  //
   // Now spin up a read thread to read packets from the tap device.
   //
   NS_ABORT_MSG_IF (m_readThread != 0,"TapBridge::StartTapDevice(): Receive thread is already running");
@@ -247,14 +255,28 @@
 {
   NS_LOG_FUNCTION_NOARGS ();
 
-  close (m_sock);
-  m_sock = -1;
+  //
+  // If the socket is open, then close it.  This will triger any running read
+  // thread to exit.
+  //
+  if (m_sock != -1)
+    {
+      close (m_sock);
+      m_sock = -1;
+    }
 
-  NS_ASSERT_MSG (m_readThread != 0, "TapBridge::StopTapDevice(): Receive thread is not running");
-
-  NS_LOG_LOGIC ("Joining read thread");
-  m_readThread->Join ();
-  m_readThread = 0;
+  //
+  // If a read thread is running, then we just told it to exit by closing its
+  // socket.  Instead of hoping for the best, we hang out until the thread 
+  // actually exits, in case it decides it needs to do something ns-3-ish
+  // before returning.
+  //
+  if (m_readThread != 0)
+    {
+      NS_LOG_LOGIC ("Joining read thread");
+      m_readThread->Join ();
+      m_readThread = 0;
+    }
 }
 
 void