Index: captcha.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/captcha/captcha.module,v
retrieving revision 1.42.2.33
diff -u -u -p -r1.42.2.33 captcha.module
--- captcha.module	20 Sep 2007 01:37:07 -0000	1.42.2.33
+++ captcha.module	22 Sep 2007 10:31:53 -0000
@@ -401,6 +401,12 @@ function captcha_form_alter($form_id, &$
     global $conf;
     $conf['cache'] = FALSE;
 
+    // make sure $_SESSION['captcha'] is an array (this is needed in some upgrade
+    // scenarios from previous versions where $_SESSION['captcha'] is a string.
+    if (!is_array($_SESSION['captcha'])) {
+      $_SESSION['captcha'] = array();
+    }
+
     // Do not present captcha if not captcha-persistent and user has already solved a captcha for this form
     if (_captcha_persistence_skip($form_id)) {
       return;