[imp] Problem in logout

[Marco Favero]

Hi all,
I installed last Horde Groupware Webmail Edition  1.2.
I notice a problem: sometime logout action fails. It returns this on syslog:

2008-09-29T16:26:47.418900+02:00 vm HORDE[22094]: [imp] Could not save 
the compiled template file 
'horde-webmail-1.2/config/../imp/templates/mailbox/header.html'. [pid 
22094 on line 231 of "horde-webmail-1.2/imp/lib/Template.php"]

The error shown by browser after logout failed is this:
"We cannot verify that this request was really sent by you. It could be 
a malicious request."

It seems this happens only with distribuited memcache system.

For better understanding, my configuration is:

$conf['memcache']['hostspec'] = array('server1', 'server2', 'server3', 
'server4', 'server5');
$conf['memcache']['port'] = array('11211');
$conf['memcache']['weight'] = array('1', '1', '1', '1', '1');
$conf['memcache']['persistent'] = true;
$conf['memcache']['compression'] = false;
$conf['memcache']['large_items'] = true;
$conf['memcache']['enabled'] = true;
$conf['sessionhandler']['memcache'] = false;
$conf['auth']['params']['app'] = 'imp';
$conf['session']['name'] = 'Horde';
$conf['session']['use_only_cookies'] = true;
$conf['session']['cache_limiter'] = 'nocache';
$conf['session']['timeout'] = 0;
$conf['cache']['default_lifetime'] = 86400;
$conf['cache']['driver'] = 'memcache';

All works well. I notice only impossibility to logout.
This problem doesn't happen on previous Horde Groupware Webmail Edition 
  1.1.3 with same configuration.

Could you help me?

Thank you very much
Marco