WordPress suddenly quit working

I have the wordpress blogs and all of them suddenly quit working with the message:

Fatal error: Call to undefined function: update_user_cache() in /home2/carltown/netadventures-www/wordpress/wp-settings.php on line 92

Using Dreamweaver, I see the code line is:

if ( !update_user_cache() && (!strstr($_SERVER[‘PHP_SELF’], ‘install.php’) && !defined(‘WP_INSTALLING’)) ) {
if ( strstr($_SERVER[‘PHP_SELF’], ‘wp-admin’) )
$link = ‘install.php’;
else
$link = ‘wp-admin/install.php’;
die(sprintf(__(“It doesn’t look like you’ve installed WP yet. Try running install.php.”), $link));
}
$wpdb->show_errors();

What happened to the user cache? The hosting site appears to have done nothing and I haven’t done anything on the server – not even a post. I did have some local system problems, but they should not have affected my host – right? i.e., there are no cookies on my system it needs. The wordpress administrator won’t come up (same error messatge) and the site blogs won’t come up on other systems.