Out of Memory when Searching

When I do a search in the search box on my site http://www.irishshopper.com I get this message

5 Out of memory (Needed 20447204 bytes)
in:
[select count(distinct p.products_id) as total FROM (products p LEFT JOIN manufacturers m USING(manufacturers_id), products_description pd, categories c, products_to_categories p2c ) LEFT JOIN meta_tags_products_description mtpd ON mtpd.products_id= p2c.products_id AND mtpd.language_id = 1 WHERE (p.products_status = 1 AND p.products_id = pd.products_id AND pd.language_id = 1 AND p.products_id = p2c.products_id AND p2c.categories_id = c.categories_id AND ((pd.products_name LIKE '%calendar%' OR p.products_model LIKE '%calendar%' OR m.manufacturers_name LIKE '%calendar%' OR (mtpd.metatags_keywords LIKE '%calendar%' AND mtpd.metatags_keywords !='') OR (mtpd.metatags_description LIKE '%calendar%' AND mtpd.metatags_description !='') OR pd.products_description LIKE '%calendar%') ))]