Google Sitemap Error

It's weird but I started getting google sitemap errors suddenly. Error message says:

Notice: Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'p.product_id ASC' at line 1
Error No: 1064
SELECT p.product_id, (SELECT AVG(rating) AS total FROM review r1 WHERE r1.product_id = p.product_id AND r1.status = '1' GROUP BY r1.product_id) AS rating FROM product p LEFT JOIN product_description pd ON (p.product_id = pd.product_id) LEFT JOIN product_to_store p2s ON (p.product_id = p2s.product_id) WHERE pd.language_id = '1' AND p.status = '1' AND p.date_available <= NOW() AND p2s.store_id = '0' GROUP BY p.product_id ORDER BY p.sort_order ASC p.product_id ASC in /..system/database/mysql.php on line 49


I'm using version 1.5.1.3 and I have not made any changes to store recently, so what might be wrong? Any help is much appreciated.

That syntax does not appear to be the 1.5.1.3 getProducts() function. I have attached the correct function, or at least one from a fresh download.

Thank you for your help. But what's the name of the file that needs to be edited. And why would it start giving problems suddenly, it was working fine for 4 months without any problems.