Index: captcha.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/captcha/captcha.module,v
retrieving revision 1.58.2.6
diff -u -r1.58.2.6 captcha.module
--- captcha.module	7 Apr 2008 22:25:45 -0000	1.58.2.6
+++ captcha.module	6 May 2008 09:30:03 -0000
@@ -113,6 +113,13 @@
       'value' => $t('Already @counter blocked form submissions', array('@counter' => variable_get('captcha_wrong_response_counter', 0))),
       'severity' => REQUIREMENT_INFO,
     );
+    if (!db_result(db_query('SELECT COUNT(*) FROM {users} WHERE uid=%d', 0))) {
+      $requirements['captcha_no_sessions_for_anonymous'] = array(
+        'title' => $t('CAPTCHA'),
+        'value' => $t('There is no entry for uid 0 in the users database table, which disables persistent session data for anonymous users. Because the CAPTCHA module depends on sessions, CAPTCHAs will not work for anonymous users.'),
+        'severity' => REQUIREMENT_ERROR,
+      );
+    }
   }
   return $requirements;
 }