diff -r 2bbe7dc920de Lib/idlelib/EditorWindow.py
--- a/Lib/idlelib/EditorWindow.py	Sat Dec 10 17:55:31 2011 -0500
+++ b/Lib/idlelib/EditorWindow.py	Tue Dec 13 20:31:59 2011 -0600
@@ -799,12 +799,20 @@
         rf_list = [path for path in rf_list if path not in bad_paths]
         ulchars = "1234567890ABCDEFGHIJK"
         rf_list = rf_list[0:len(ulchars)]
-        rf_file = open(self.recent_files_path, 'w',
+        try:
+            rf_file = open(self.recent_files_path, 'w',
                         encoding='utf_8', errors='replace')
-        try:
-            rf_file.writelines(rf_list)
-        finally:
-            rf_file.close()
+        except IOError as err:
+            tkMessageBox.showerror(title='IDLE Error',
+                   message='Unable to open Recent Files list for writing:\n%s' % str(err),
+                   parent=self.text)
+        else:            
+            try:
+                rf_file.writelines(rf_list)
+            finally:
+                rf_file.close()
+
+            
         # for each edit window instance, construct the recent files menu
         for instance in self.top.instance_dict:
             menu = instance.recent_files_menu