Did you ever get this problem solved. My downloads were working until we installed a contribution (Not sure which one) and since then we've been having the same problem:
1054 - Unknown column 'DOWNLOAD_AVAILABLE_DATE' in 'field list'
SELECT DATE_FORMAT(DOWNLOAD_AVAILABLE_DATE, '%Y-%m-%d') as date_purchased_day, opd.download_maxdays, op.products_name, opd.orders_products_download_id, opd.orders_products_filename, opd.download_count, opd.download_maxdays FROM orders o, orders_products op, orders_products_download opd WHERE customers_id = '2' AND o.orders_status >= DOWNLOADS_AVAILABLE_STATUS AND o.orders_id = '43' AND op.orders_id = '43' AND opd.orders_products_id=op.orders_products_id AND opd.orders_products_filename<>''
[TEP STOP]