Critical Error: An error occured while executing a MySQL-Query (

INSERT INTO    counter
                                                         (counterDate, counterVisits, counterImpressions)
                                          VALUES         (CURDATE(), 0, 0)

). MySQL says: Duplicate entry '0' for key 'PRIMARY'(1062), thrown in line 560 in file /home/localxi/www/localx.info/modules/MysqlWrapper.class.php (class: MySQLWrapper)