Prestashop 1.5 HTTP 500 ERROR

My online shop uses Prestashop 1.5. Some how the website returns a blank page. I use Chrome Browser and see a HPPT 500 ERROR message. I checked the error log through CPANLE file manager and the latest error are shown as below:

PHP Deprecated: Function get_magic_quotes_gpc() is deprecated in /home/pxchanger/public_html/store/config/defines.inc.php on line 145
PHP Fatal error: Uncaught Error: [] operator not supported for strings in /home/pxchanger/public_html/store/classes/db/DbQuery.php:96
Stack trace:
#0 /home/pxchanger/public_html/store/Adapter/Adapter_EntityMapper.php(45): DbQueryCore->from('shop', 'a')
#1 /home/pxchanger/public_html/store/classes/ObjectModel.php(233): Adapter_EntityMapper->load('1', NULL, Object(Shop), Array, NULL, true)
#2 /home/pxchanger/public_html/store/classes/shop/Shop.php(131): ObjectModelCore->__construct('1', NULL, NULL)
#3 /home/pxchanger/public_html/store/classes/shop/Shop.php(397): ShopCore->__construct('1')
#4 /home/pxchanger/public_html/store/config/config.inc.php(114): ShopCore::initialize()
#5 /home/pxchanger/public_html/store/index.php(27): require('/home/pxchanger...')
#6 {main}
thrown in /home/pxchanger/public_html/store/classes/db/DbQuery.php on line 96