diff -up hplip-3.9.12/ui4/devmgr5.py.preferences-crash hplip-3.9.12/ui4/devmgr5.py
--- hplip-3.9.12/ui4/devmgr5.py.preferences-crash	2009-12-15 21:22:17.000000000 +0000
+++ hplip-3.9.12/ui4/devmgr5.py	2010-01-20 12:21:27.794561868 +0000
@@ -2020,7 +2020,9 @@ class DevMgr5(QMainWindow,  Ui_MainWindo
         if dlg.exec_() == QDialog.Accepted:
             self.user_settings.load()
 
-            self.cur_device.sendEvent(EVENT_USER_CONFIGURATION_CHANGED, self.cur_printer)
+            if self.cur_device is not None:
+                self.cur_device.sendEvent(EVENT_USER_CONFIGURATION_CHANGED,
+                                          self.cur_printer)
 
 
     # ***********************************************************************************