Some errors when I save my content I have some errors when I try to validate my content, I add a lot a modules at the same time, and I don't know witch module causes this error. I uninstalled some of them without success, Is it some explanation in the following errors for the specialists you are?

Notice : Undefined property: stdClass::$is_new dans node_save() (ligne 1108 dans /var/www/V1/modules/node/node.module).

Notice : Undefined property: stdClass::$is_new dans node_save() (ligne 1134 dans /var/www/V1/modules/node/node.module).

Notice : Undefined property: stdClass::$is_new dans node_save() (ligne 1140 dans /var/www/V1/modules/node/node.module).

PDOException : SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'nid' cannot be null: INSERT INTO {location_instance} (nid, vid, uid, genid, lid) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array ( [:db_insert_placeholder_0] =&gt; [:db_insert_placeholder_1] =&gt; [:db_insert_placeholder_2] =&gt; 0 [:db_insert_placeholder_3] =&gt; cck:field_endroit: [:db_insert_placeholder_4] =&gt; 9 ) dans location_save_locations() (ligne 1132 dans /var/www/V1/modules/location/location.module).
The error is related to the location module. Uninstalling that module will remove the errors.