error_reporting(E_ALL | E_STRICT);
ini_set('display_errors', true);

$httpheader = array(
  'Accept: text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1',
  'User-Agent: Opera/9.80',
  'Accept-Language: ru-RU,ru;q=0.9,en;q=0.8',
  'Accept-Charset: iso-8859-1, utf-8, utf-16, *;q=0.1',
  'Accept-Encoding: deflate, gzip, x-gzip, identity, *;q=0', // если это, то потом   if($temp = @gzinflate(substr($result, 10))) $result = $temp;
  'Referer: '.$referer,
  'TE: deflate, gzip, chunked, identity, trailers',
);
curl_setopt($ch, CURLOPT_HTTPHEADER, $httpheader);

curl_setopt ($ch, CURLOPT_POSTFIELDS, array('login' => 'test', 'pass' => 'test')); // всегда так делаю.

if(curl_errno($ch)){
  echo curl_errno($ch).', '.curl_error($ch);
}

<?php
error_reporting(E_ALL | E_STRICT);
ini_set('display_errors', true);

define('MY_ROOT', str_replace('\\', '/', dirname(__FILE__)));

$httpheader = array(
  'Accept: text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1',
  'User-Agent: Opera/9.80',
  'Accept-Language: ru-RU,ru;q=0.9,en;q=0.8',
  'Accept-Charset: iso-8859-1, utf-8, utf-16, *;q=0.1',
  'Accept-Encoding: deflate, gzip, x-gzip, identity, *;q=0',
  'Referer: http://loadpays.com/',
  'TE: deflate, gzip, chunked, identity, trailers',
);
$ch = curl_init("http://loadpays.com/?p=login");
curl_setopt($ch, CURLOPT_HTTPHEADER, $httpheader);
curl_setopt($ch, CURLOPT_TIMEOUT, 60);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_COOKIEJAR, MY_ROOT."/cookie.txt");
curl_setopt($ch, CURLOPT_COOKIEFILE, MY_ROOT."/cookie.txt");
curl_setopt($ch, CURLOPT_POSTFIELDS, "login=xxx&password=yyy");
curl_setopt($ch, CURLOPT_POST, 1);
$result = curl_exec($ch);
if(curl_errno($ch)){
  die(curl_errno($ch).', '.curl_error($ch));
}
curl_close($ch);
if($temp = @gzinflate(substr($result, 10))) $result = $temp;
echo $result;
?>

curl_setopt($ch, CURLOPT_HEADER, 1);

<?php
function get_curl($url, $postdata = '', $max_redirect = 7){
  if(!$max_redirect) return;
  $max_redirect--;
  $ch = curl_init($url);
  curl_setopt($ch, CURLOPT_TIMEOUT, 60);  
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_COOKIEJAR, MY_ROOT."/cookie.txt");
  curl_setopt($ch, CURLOPT_COOKIEFILE, MY_ROOT."/cookie.txt");
  if($postdata){
    curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata);
    curl_setopt($ch, CURLOPT_POST, 1);
  }
  $result = curl_exec($ch);
  if(curl_errno($ch)){
    die(curl_errno($ch).', '.curl_error($ch));
  }
  $info = curl_getinfo($ch);
  curl_close($ch);
  if($info['redirect_url']) return get_curl($info['redirect_url'], null, $max_redirect);
  return $result;
}
echo get_curl('http://loadpays.com/?p=login', 'login=xxx&password=yyy', 7);

function get_loadpays($url, $postdata = ''){
  $max_redirect = 7;
  $result = '';
  for(; $max_redirect >= 0; $max_redirect--){
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_TIMEOUT, 60);  
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_COOKIEJAR, MY_ROOT."/cookie.txt");
    curl_setopt($ch, CURLOPT_COOKIEFILE, MY_ROOT."/cookie.txt");
    if($postdata){
      curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata);
      curl_setopt($ch, CURLOPT_POST, 1);
    }
    $result = curl_exec($ch);
    if(curl_errno($ch)){
      die(curl_errno($ch).', '.curl_error($ch));
    }
    $info = curl_getinfo($ch);
    if(!$info['redirect_url']) break;
    $url = $info['redirect_url'];
    $postdata = '';
  }
  curl_close($ch);
  return $result;
}
echo get_loadpays('http://loadpays.com/?p=login', 'login=xxx&password=yyy');
?>

Warning: curl_setopt() [function.curl-setopt]: CURLOPT_FOLLOWLOCATION cannot be activated when safe_mode is enabled or an open_basedir is set in...

HTTP/1.1 302 Found Server: nginx/1.2.3 Date: Thu, 12 Sep 2013 09:27:49 GMT Content-Type: text/html Content-Length: 20 Connection: keep-alive X-Powered-By: PHP/5.4.6 Expires: Thu, 19 Nov 1981 08:52:00 GMT Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma: no-cache Location: /member/ Content-Encoding: gzip Vary: Accept-Encoding ‹

Notice: Undefined index: redirect_url in...

Notice: Undefined index: redirect_url in...

function get_loadpays($url, $postdata = ''){
  $max_redirect = 7;
  $result = '';
  $ch = curl_init();
  for(; $max_redirect >= 0; $max_redirect--){
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HEADER, 1);
    curl_setopt($ch, CURLOPT_TIMEOUT, 60);  
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_COOKIEJAR, MY_ROOT."/cookie.txt");
    curl_setopt($ch, CURLOPT_COOKIEFILE, MY_ROOT."/cookie.txt");
    if($postdata){
      curl_setopt($ch, CURLOPT_POSTFIELDS, $postdata);
      curl_setopt($ch, CURLOPT_POST, 1);
    }
    $result = curl_exec($ch);
    if(curl_errno($ch)){
      die(curl_errno($ch).', '.curl_error($ch));
    }
    $temp   = explode("\r\n\r\n", $result);
    $header = array_shift($temp);
    $result = implode("\r\n\r\n", $temp);
    if(preg_match('/Location:(.*?)\n/', $header, $matches)){
      $postdata = '';
      $parse_url = parse_url($url);
      $url = $parse_url['scheme'].'://'.$parse_url['host'].trim($matches[1]);
    }
    else break;
  }
  curl_close($ch);
  return $result;
}
echo get_loadpays('http://loadpays.com/?p=login', 'login=zzz&password=xxx');