Subqueries are not supported in MySQL 4.0, the first version where it worked was 4.1.
But why do you use a subquery? I think that a simple join would solve your problem:
SELECT *
FROM tbl_product
INNER JOIN tbl_company ON tbl_company.company_id = tbl_product.company_id
WHERE tbl_product.subcategory_id = '10'
ORDER BY tbl_company.company_name
By the way, only select the columns that you need.