diff --git a/reference/session/reference.xml b/reference/session/reference.xml
index 936f622b11..5110b052f9 100644
--- a/reference/session/reference.xml
+++ b/reference/session/reference.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.30 $ -->
+<!-- $Revision: 1.31 $ -->
  <reference id="ref.session">
   <title>Session handling functions</title>
   <titleabbrev>Sessions</titleabbrev>
@@ -26,13 +26,23 @@
     <para>
      The session support allows you to register arbitrary numbers of
      variables to be preserved across requests. When a visitor accesses
-     your site, PHP will check automatically (if session.auto_start is
-     set to 1) or on your request (explicitly through
+     your site, PHP will check automatically (if <link 
+     linkend="ini.session.auto_start"><literal>session.auto_start</literal></link>
+     is set to 1) or on your request (explicitly through
      <function>session_start</function> or implicitly through
      <function>session_register</function>) whether a specific session
      id has been sent with the request. If this is the case, the prior
      saved environment is recreated.
     </para>
+     <caution>
+      <para>
+       If you do turn on <link linkend="ini.session.auto_start">
+       <literal>session.auto_start</literal></link> then you cannot put
+       objects into your sessions since the class definition has to be
+       loaded before starting the session in order to recreate the
+       objects in your session.
+      </para>
+     </caution>
     <para>
      All registered variables are serialized after the request
      finishes.  Registered variables which are undefined are marked as