I've just noticed your expecting to use "sCurrentMode" as the index of an array.
Code:
$config['sCurrentMode'] = 'books';
// Sort Types
$config['arModeSortType']['baby'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
);
$config['arModeSortType']['books'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+reviewrank' => 'Average Customer Review',
'+pricerank' => 'Price (Low to High)',
'+inverse-pricerank' => 'Price (High to Low)',
'+daterank' => 'Publication Date',
'+titlerank' => 'Alphabetical (A-Z)',
'-titlerank' => 'Alphabetical (Z-A)',
);
$config['arModeSortType']['classical'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
);
$config['arModeSortType']['dvd'] = array (
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical',
);
$config['arModeSortType']['electronics'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical',
'+reviewrank' => 'Review',
);
$config['arModeSortType']['garden'] = array (
'+psrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
'-titlerank' => 'Alphabetical (Z-A)',
'+manufactrank' => 'Manufacturer (A-Z)',
'-manufactrank' => 'Manufacturer (Z-A)',
'+price' => 'Price (Low to High)',
'-price' => 'Price (High to Low)',
);
$config['arModeSortType']['kitchen'] = array (
'+psrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
'-titlerank' => 'Alphabetical (Z-A)',
'+manufactrank' => 'Manufacturer (A-Z)',
'-manufactrank' => 'Manufacturer (Z-A)',
'+price' => 'Price (Low to High)',
'-price' => 'Price (High to Low)',
);
$config['arModeSortType']['magazines'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
);
$config['arModeSortType']['music'] = array (
'+psrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+artistrank' => 'Artist Name',
'+orig-rel-date' => 'Original Release Date',
'+titlerank' => 'Alphabetical',
);
$config['arModeSortType']['pc-hardware'] = array (
'+psrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
'-titlerank' => 'Alphabetical (Z-A)',
);
$config['arModeSortType']['photo'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
'-titlerank' => 'Alphabetical (Z-A)',
);
$config['arModeSortType']['software'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical',
'+price' => 'Price (Low to High)',
'+price' => 'Price (High to Low)',
);
$config['arModeSortType']['toys'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
);
$config['arModeSortType']['universal'] = array (
'+psrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical (A-Z)',
'-titlerank' => 'Alphabetical (Z-A)',
'+manufactrank' => 'Manufacturer (A-Z)',
'-manufactrank' => 'Manufacturer (Z-A)',
'+price' => 'Price (Low to High)',
'-price' => 'Price (High to Low)',
);
$config['arModeSortType']['vhs'] = array (
'+psrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical',
);
$config['arModeSortType']['videogames'] = array (
'+pmrank' => 'Featured Items',
'+salesrank' => 'Bestselling',
'+titlerank' => 'Alphabetical',
'+price' => 'Price (Low to High)',
'-price' => 'Price (High to Low)',
);