Is CB login module published and joomlas unpublished?

YES
Is CB registration independent of joomlas?

YES
Is your webhost using the latest PHP5?

YES
Is CB and Joomla up to date?

YES
Is your CB default template enabled in plugin management?

YES
Does using default joomla template resolve your issue?
NO
Have you disabled CB plugins 1 by 1 until resolved work?

YES
Have you disabled Joomla modules 1 by 1 until resolved work?

YES
Have you disabled Joomla plugins 1 by 1 until resolved work?

YES
Have you ran all CB tools? (should be all green)

yes
Does a fresh Joomla and CB install work? (in subfolder without replacing current site)

YES
Is your webhost PHP memory limit set high enough? (memory_limit)
YES
Is your webhost PHP timeout limit set high enough? (max_execution_time)
?
YES
Have you checked permissions from joomla backend? (should be all green)

YES
Have you unziped and repacked com_comprofiler.zip before installing?

YES
Have you disabled and purged Joomla cache?

YES
Have you disabled and purged Browser cache?

YES
Have you disabled and purged host cache?

YES
Have you disabled sef

YES

Exact PHP version.
5.2.6-1+lenny9
Exact CB version.
1.2.3
Exact Joomla version.
1.5.20
Detailed description of problem. (screenshots? link?)
www.bio-log.fr/portail/index.php?option=com_comprofiler&task=registers


Any error messages reported with Joomla debug mode on and error reporting set to maximum?
NO
Any error messages reported with your hosts error log?

NO
Any ACL modification components? (JACL, etc..)

NO
Any SEF components?

NO
Move or encrypt configuration.php?
???
don’t know what does it mean
Upgrade from CB version ?? or fresh install?

fresh install
Migrated from Joomla version ?? or fresh install?

Fresh install
What browser is issue present in?

Firefox, Safari, chrome

so now as I replied to you item by item
please tell me exactly what screenshot or anything else, you are waiting because there are so many to show,....