Index: src/orca/orca.py
===================================================================
--- src/orca/orca.py	(revision 3919)
+++ src/orca/orca.py	(working copy)
@@ -180,7 +180,8 @@
 
     # If this event is not for the currently active script, then just return.
     #
-    if event and event.source and orca_state.activeScript:
+    if event and event.source and \
+       event.host_application and orca_state.activeScript:
         currentApp = orca_state.activeScript.app.name
         if currentApp != event.host_application.name and \
            currentApp != event.source.getApplication().name:
