Failed to execute the SQL query

select  i.title,  c.title, c.id, c.siteurl, i.unread, i.url, i.enclosure, i.author, i.description, c.icon,  unix_timestamp(ifnull(i.pubdate,i.added)) as ts,  i.pubdate is not null as ispubdate, i.id, r.rating, c.issponsor   from  co_item  i  left join  co_rating  r on (i.id = r.iid),  co_channels  c,  co_folders  f  where  i.cid = c.id and  f.id=c.parent and  not(i.unread & 8) and  not(i.unread & 4) and i.cid = 58 and IF(i.pubdate IS NOT NULL, i.pubdate <= now(), i.added <= now())  and  1=1  order by  ts desc, f.position asc, c.position asc , ts desc, i.id asc limit  0, 50

Error 2013: Lost connection to MySQL server during query