error 1242Error: Subquery returns more than 1 row any help

When trying to edit any product from admin dashboard i found the following error
Warning: mysql_query(): Unable to save result set in /hermes/bosnaweb05a/b4/ipg.macrolid/system/database/mysql.php on line 22Notice: Error: Subquery returns more than 1 row
Error No: 1242
SELECT DISTINCT *, (SELECT keyword FROM oc_url_alias WHERE query = 'product_id=73') AS keyword FROM oc_product p LEFT JOIN oc_product_description pd ON (p.product_id = pd.product_id) WHERE p.product_id = '73' AND pd.language_id = '1' in /hermes/bosnaweb05a/b4/ipg.macrolid/system/database/mysql.php on line 50
Any one can solve this problem

Check your DB table "oc_url_alias" and find query = 'product_id=73'. If show more than one result you must delate one of them.

I already do that but the problem is frequent and presistant what's the cause and how to correct it permenantly