Have you independently verified that memcache is in fact not working?
Run the following script twice to confirm memcache's functionality:
PHP Code:
<?php
$mem = new Memcached();
$mem->addServer("127.0.0.1", 11211);
$result = $mem->get("blah");
if ($result) {
echo $result;
} else {
echo "No matching key found. I'll add that now!";
$mem->set("blah", "I am data! I am held in memcached!") or die("Couldn't save anything to memcached...");
}
?>