[phpGroupWare-developers] mcrypt_generic() errors with addressbook and property with HEAD

[Maat]

here is the error :

ERROR Warning: mcrypt_generic() [function.mcrypt-generic
<http://localhost/phpgroupwarehead3/function.mcrypt-generic>]: An empty
string was passed in
/path/to/phpgroupware/phpgwapi/inc/class.crypto.inc.php at line 149*

it's on a fresh install of phpgroupware HEAD juste when clicking the menu link 
of property  or the add button of addressbook

system : mdv linux cooker x86_64 + php5.2.3 (with mcrypt module installed and 
enabled) + mysql5.0.45 

help or tips are welcome :-/