strange... try downloading the admin plugin, and putting this in the admin plugin box:
qa_db_query_sub(
'CREATE TABLE IF NOT EXISTS ^usermeta (
meta_id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
user_id bigint(20) unsigned NOT NULL,
meta_key varchar(255) DEFAULT NULL,
meta_value longtext,
PRIMARY KEY (meta_id),
UNIQUE (user_id,meta_key)
) ENGINE=MyISAM DEFAULT CHARSET=utf8'
);
Edit: if you can't access admin/plugins, try putting the above code in the theme-switcher's qa-plugin.php, right after the opening <?php tag.