I appreciate that this early version has security issues, but it has been working for the last 6/7 years without issue.

My problem has only recently come to light, possibly after I backed up the database in August, but not exactly sure.

Access to the home page of the website is compromised, see
http://www.mainzone.co.uk

and the following error displayed

1064 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 ')' at line 1
in:
[INSERT INTO user_adverts_map(CUSTOMER_ID, last_viewed_product_id) VALUES('0',)]

I have never restored the database before and I will read up before attempting anything too advanced. Any advice gratefully accepted, thanks.