composer.json に fosuserbundle をインストールしようとしていますが、この問題がコンソールに表示されます。
C:\xamppHE\php>php composer.phar install
Fatal error: Uncaught exception 'ErrorException' with message 'proc_open(): Crea
teProcess failed, error code - 0' in phar://C:/xamppHE/php/composer.phar/vendor/
symfony/console/Symfony/Component/Console/Application.php on line 1013
ErrorException: proc_open(): CreateProcess failed, error code - 0 in phar://C:/x
amppHE/php/composer.phar/vendor/symfony/console/Symfony/Component/Console/Applic
ation.php on line 1013
Call Stack:
0.0140 235464 1. {main}() C:\xamppHE\php\composer.phar:0
0.0150 234136 2. require('phar://C:/xamppHE/php/composer.phar/bin/comp
oser') C:\xamppHE\php\composer.phar:15
0.4280 2045032 3. Composer\Console\Application->run() phar://C:/xamppHE
/php/composer.phar/bin/composer:43
0.4570 2262672 4. Symfony\Component\Console\Application->run() phar://C
:/xamppHE/php/composer.phar/src/Composer/Console/Application.php:83
0.8780 2717120 5. Composer\Console\Application->renderException() phar:
//C:/xamppHE/php/composer.phar/vendor/symfony/console/Symfony/Component/Console/
Application.php:128
1.1730 2732960 6. Symfony\Component\Console\Application->renderExceptio
n() phar://C:/xamppHE/php/composer.phar/src/Composer/Console/Application.php:163
1.1730 2733808 7. Symfony\Component\Console\Application->getTerminalWid
th() phar://C:/xamppHE/php/composer.phar/vendor/symfony/console/Symfony/Componen
t/Console/Application.php:731
1.1730 2733824 8. Symfony\Component\Console\Application->getTerminalDim
ensions() phar://C:/xamppHE/php/composer.phar/vendor/symfony/console/Symfony/Com
ponent/Console/Application.php:797
1.1740 2734024 9. Symfony\Component\Console\Application->getConsoleMode
() phar://C:/xamppHE/php/composer.phar/vendor/symfony/console/Symfony/Component/
Console/Application.php:827
1.1740 2735320 10. proc_open() phar://C:/xamppHE/php/composer.phar/vendo
r/symfony/console/Symfony/Component/Console/Application.php:1013
1.1780 2736152 11. Composer\Util\ErrorHandler::handle() phar://C:/xamppH
E/php/composer.phar/vendor/symfony/console/Symfony/Component/Console/Application
.php:1013
Symfony のバージョンは 2.3.5、PHP は 5.4.19、OS は Windows Vista です。私は何をすべきか？ありがとう！