system:
Linux web 2.6.27.21-0.1-pae #1 SMP 2009-03-31 14:50:44 +0200 i686 i686 i386 GNU/Linux PHP Version 5.3.8 Apache Version Apache/2.2.21 (Linux/SUSE)
This is a error with compatibility of the runtime oracle 11g and PHP Oci support. As the OP confirm, the downgrade of the client to 10g works. The solution was found here.