Php – Memcached extension error in PHP

yesterday i migrated to Rackspace (CentOS 5.5). Everything was already configured (apache, php, mysql, memcached) and working well.

The only thing i forgot, and installed at last was the mail server (iRedMail). After that, for some reason, memcached got kind of screwed up:

[root@mail php.d]# php -v

PHP Warning:  PHP Startup: memcache: Unable to initialize module
Module compiled with module API=20050922, debug=0, thread-safety=0
PHP    compiled with module API=20060613, debug=0, thread-safety=0
These options need to match
 in Unknown on line 0
PHP 5.2.10 (cli) (built: Nov 13 2009 11:44:05)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies

I tried reinstalling memcached:

yum install memcached
yum install php-pecl-memcache
service httpd restart

But the error message kept being displayed.

I am pointing to this extension in the php.ini extension=memcache.so and memcache.so is inside /usr/lib64/php/modules (extensions directory). A friend told me to check for missing library dependencies:

[root@mail modules]# ldd -v memcache.so

linux-vdso.so.1 =>  (0x00007fff4e915000)
libc.so.6 => /lib64/libc.so.6 (0x00007f5b90c2b000)
/lib64/ld-linux-x86-64.so.2 (0x0000003aa6800000)

Version information:
./memcache.so:
    libc.so.6 (GLIBC_2.4) => /lib64/libc.so.6
    libc.so.6 (GLIBC_2.3) => /lib64/libc.so.6
    libc.so.6 (GLIBC_2.2.5) => /lib64/libc.so.6
/lib64/libc.so.6:
    ld-linux-x86-64.so.2 (GLIBC_2.3) => /lib64/ld-linux-x86-64.so.2
    ld-linux-x86-64.so.2 (GLIBC_PRIVATE) => /lib64/ld-linux-x86-64.so.2

Does that linux-vdso.so.1 something to do with my problem? If so, how do i install it? If not, what else could be causing this behavior?

Thanks for your help.