|Error: Failed to set key: Failed to set key: cache_page-......||Upgrade your PECL library to PECL package (2.2.1) (or higher).
|Warning: Zlib compression at the php.ini level conflicts with Memcache.
|Cache isn't flushed correctly.||
PECL memcache 3.0.4 has a known bug that causes wildcard flushes to fail. Update to the latest PECL memcache package.
You'll be affected from this bug if you use Ubuntu Lucid or Debian 6.
To update Ubuntu-Lucid proceed like that: