PDOException : Integrity constraint violation

Hello,

I'm working under Drupal 7.12 and Pathauto 7.x-1.0, and when i attempt to activate (or desactivate) the PathAuto module, I got this nasty error :

Error message:
PDOException : SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'DrupalCacheArray-class' for key 'PRIMARY': INSERT INTO {registry} (name, type, filename, module, weight) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4), (:db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9); Array ( [:db_insert_placeholder_0] => DrupalCacheArray [:db_insert_placeholder_1] => class [:db_insert_placeholder_2] => includes/bootstrap - Copy.inc [:db_insert_placeholder_3] => [:db_insert_placeholder_4] => 0 [:db_insert_placeholder_5] => SchemaCache [:db_insert_placeholder_6] => class [:db_insert_placeholder_7] => includes/bootstrap - Copy.inc [:db_insert_placeholder_8] => [:db_insert_placeholder_9] => 0 ) dans _registry_parse_file() (ligne 179 dans /homez.517/foo/www/includes/registry.inc).

Afterwhile, the module appears to be activated in the Module page, but I can't get through its settings.
When I try to access them directly in Admin / Configuration / URL Aliases, ain't no "Patterns" options there.

In first place I thought it was due to another module, which might have already inserted this table, but I have no method to diagnosticate which one is guilty.

How can I proceed to make Pathauto working? Does someone have a clue for debugging?

Thanks,

RAF