last_login is not an IMP preference. You probably upgraded from an IMP 
3 version and didn't follow the upgrade instructions.

Background:

I'm using the Horde-Framwork with imp-Authentification.

The preferencies backend is LDAP.



When I'm including ingo in imp then the last_login preference is not stored!



Reason:

- The imp-preferencies are loaded (old value for last_login is retrieved)

- Auth.php sets the new value for last_login

- Then the ingo-preferencies are loaded and overwrite the new value 
for last_login



Resolution:

Store the new "dirty-value" for last_login after setting it:



Code snippet:

      // Set the user's last_login information.

      $last_login = array('time' => time(),

                                    'host' => 
@gethostbyaddr($_SERVER['REMOTE_ADDR']));

      $GLOBALS['prefs']->setValue('last_login', serialize($last_login));

      //NEW: ************************Store it ! *********************

      $GLOBALS['prefs']->store();