diff -r e159cb0d955b Doc/library/site.rst
--- a/Doc/library/site.rst	Sun Apr 27 10:44:46 2014 -0700
+++ b/Doc/library/site.rst	Sun Apr 27 22:35:49 2014 -0700
@@ -101,6 +101,12 @@
 directory.  If this import fails with an :exc:`ImportError` exception, it is
 silently ignored.
 
+If Python is started without output streams available, as with
+:file:`pythonw.exe` on Windows (which is used by default to start IDLE),
+attempted output from :mod:`sitecustomize` is ignored. Any exception other
+than :exc:`ImportError` causes a silent and perhaps mysterious failure of the
+process.
+
 .. index:: module: usercustomize
 
 After this, an attempt is made to import a module named :mod:`usercustomize`,