Error when editing users

Dear experts,

For some reason I am unable to edit users on my drupal 7 installation. Everytime I try to update anything on an user account I get this error:

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'user-28-0-page_manager' for key 'PRIMARY': INSERT INTO {panelizer_entity} (entity_type, entity_id, revision_id, did, view_mode) 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] => user [:db_insert_placeholder_1] => 28 [:db_insert_placeholder_2] => 0 [:db_insert_placeholder_3] => 0 [:db_insert_placeholder_4] => page_manager ) in drupal_write_record()

Do you know how can I work around on that error?

Thanks in advance,

Winter