after upgrading from PHP5.2.6 to php 5.3. it seams, I also have to reinstall the PHP memcache-module.
So I downloaded the newest version of memcache (3.0.6) and followed this do
To me this error was caused due to php without support for ssl.
Enable openssl or recompile with openssl built int.
Check php support in a Linux host run
php -i | grep openssl
Should print a line with openssl if support enabled.