My osCommerce installation of PHP 4 isn't working?

Please follow the procedures below.

Edit .htaccess in public_html
Enter the following contents:

php_flag register_globals on
php_flag register_long_arrays on

Edit: [installation_dir]/admin/includes/classes/upload.php
Replace the following on Line 31:
$this = null;

To:
// $this = null;

Edit: [installation_dir]/index.php
Find this:

// show the products of a specified manufacturer
   if (isset($HTTP_GET_VARS['manufacturers_id'])) {
     if (isset($HTTP_GET_VARS['filter_id']) && tep_not_null($HTTP_GET_VARS['filter_id'])) {
// We are asked to show only a specific category
       $listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from " . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_MANUFACTURERS . " m, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and p.manufacturers_id = m.manufacturers_id and m.manufacturers_id = '" . (int)$HTTP_GET_VARS['manufacturers_id'] . "' and p.products_id = p2c.products_id and pd.products_id = p2c.products_id and pd.language_id = '" . (int)$languages_id . "' and p2c.categories_id = '" . (int)$HTTP_GET_VARS['filter_id'] . "'";
     } else {
// We show them all
       $listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from " . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_MANUFACTURERS . " m left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and pd.products_id = p.products_id and pd.language_id = '" . (int)$languages_id . "' and p.manufacturers_id = m.manufacturers_id and m.manufacturers_id = '" . (int)$HTTP_GET_VARS['manufacturers_id'] . "'";
     }
   } else {
// show the products in a given categorie
     if (isset($HTTP_GET_VARS['filter_id']) && tep_not_null($HTTP_GET_VARS['filter_id'])) {
// We are asked to show only specific catgeory
       $listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from " . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_MANUFACTURERS . " m, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and p.manufacturers_id = m.manufacturers_id and m.manufacturers_id = '" . (int)$HTTP_GET_VARS['filter_id'] . "' and p.products_id = p2c.products_id and pd.products_id = p2c.products_id and pd.language_id = '" . (int)$languages_id . "' and p2c.categories_id = '" . (int)$current_category_id . "'";
     } else {
// We show them all
       $listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_PRODUCTS . " p left join " . TABLE_MANUFACTURERS . " m on p.manufacturers_id = m.manufacturers_id, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and p.products_id = p2c.products_id and pd.products_id = p2c.products_id and pd.language_id = '" . (int)$languages_id . "' and p2c.categories_id = '" . (int)$current_category_id . "'";
     }
   }

Replace it with:

// show the products of a specified manufacturer
if (isset($HTTP_GET_VARS['manufacturers_id'])) {
if (isset($HTTP_GET_VARS['filter_id']) && tep_not_null($HTTP_GET_VARS['filter_id'])) {
// We are asked to show only a specific category
$listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from (" . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_MANUFACTURERS . " m, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c ) left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and p.manufacturers_id = m.manufacturers_id and m.manufacturers_id = '" . (int)$HTTP_GET_VARS['manufacturers_id'] . "' and p.products_id = p2c.products_id and pd.products_id = p2c.products_id and pd.language_id = '" . (int)$languages_id . "' and p2c.categories_id = '" . (int)$HTTP_GET_VARS['filter_id'] . "'";
} else {
// We show them all
$listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from (" . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_MANUFACTURERS . " m) left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and pd.products_id = p.products_id and pd.language_id = '" . (int)$languages_id . "' and p.manufacturers_id = m.manufacturers_id and m.manufacturers_id = '" . (int)$HTTP_GET_VARS['manufacturers_id'] . "'";
}
} else {
// show the products in a given categorie
if (isset($HTTP_GET_VARS['filter_id']) && tep_not_null($HTTP_GET_VARS['filter_id'])) {
// We are asked to show only specific catgeory
$listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from (" . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_MANUFACTURERS . " m, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c) left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and p.manufacturers_id = m.manufacturers_id and m.manufacturers_id = '" . (int)$HTTP_GET_VARS['filter_id'] . "' and p.products_id = p2c.products_id and pd.products_id = p2c.products_id and pd.language_id = '" . (int)$languages_id . "' and p2c.categories_id = '" . (int)$current_category_id . "'";
} else {
// We show them all
$listing_sql = "select " . $select_column_list . " p.products_id, p.manufacturers_id, p.products_price, p.products_tax_class_id, IF(s.status, s.specials_new_products_price, NULL) as specials_new_products_price, IF(s.status, s.specials_new_products_price, p.products_price) as final_price from ((" . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_PRODUCTS . " p) left join " . TABLE_MANUFACTURERS . " m on p.manufacturers_id = m.manufacturers_id, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c) left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id where p.products_status = '1' and p.products_id = p2c.products_id and pd.products_id = p2c.products_id and pd.language_id = '" . (int)$languages_id . "' and p2c.categories_id = '" . (int)$current_category_id . "'";
}
}

Edit: [installation_dir]/advanced_search_result.php
Find this:

$from_str = "from " . TABLE_PRODUCTS . " p left join " . TABLE_MANUFACTURERS . " m using(manufacturers_id), " . TABLE_PRODUCTS_DESCRIPTION . " pd left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id, " . TABLE_CATEGORIES . " c, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c";

Replace it with:

$from_str = "from ((" . TABLE_PRODUCTS . " p) left join " . TABLE_MANUFACTURERS . " m using(manufacturers_id), " . TABLE_PRODUCTS_DESCRIPTION . " pd) left join " . TABLE_SPECIALS . " s on p.products_id = s.products_id, " . TABLE_CATEGORIES . " c, " . TABLE_PRODUCTS_TO_CATEGORIES . " p2c";

If you require any further assistance on this issue, please do not hesitate to create a support ticket by sending an email to support@extremewebtechnologies.com.