--- a/Beremiz.py	Thu Dec 10 09:34:55 2009 +0100
+++ b/Beremiz.py	Thu Dec 10 09:35:39 2009 +0100
@@ -518,7 +518,8 @@
     
     def OnCloseFrame(self, event):
         if self.PluginRoot is None or self.CheckSaveBeforeClosing(_("Close Application")):
-            self.PluginRoot.KillDebugThread()
+            if self.PluginRoot is not None:
+                self.PluginRoot.KillDebugThread()
             self.KillLocalRuntime()
             event.Skip()
         else: