Если вы видите следующие ошибки в логе apache( /var/log/apache2/error.log )

[Mon Jul 15 19:43:46 2013] [notice] Apache/2.2.22 (Debian) mod_fcgid/2.3.6 PHP/5.4.4-14+deb7u2 configured — resuming normal operations
[Mon Jul 15 19:43:53 2013] [error] [client 192.168.1.49] SoftException in Application.cpp:350: UID of script «/var/www/phptest.php» is smaller than min_uid, referer: http://192.168.1.12/
[Mon Jul 15 19:43:53 2013] [error] [client 192.168.1.49] Premature end of script headers: phptest.php, referer: http://192.168.1.12/
[Mon Jul 15 19:43:53 2013] [error] [client 192.168.1.49] SoftException in Application.cpp:350: UID of script «/var/www/phptest.php» is smaller than min_uid, referer: http://192.168.1.12/

Удалите расширение:

apt-get remove suphp*