Lo dicevo che era un problema di mysql ....

avrai una versione diversa tra casa e ufficio.....
codice:
......
`Create_tmp_table_priv` enum('N','Y') character set utf8 NOT NULL default 'N',\n
`Lock_tables_priv` enum('N','Y') character set utf8 NOT NULL default 'N',\n
`Execute_priv` enum('N','Y') character set utf8 NOT NULL default 'N',\n
`Repl_slave_priv` enum('N','Y') character set utf8 NOT NULL default 'N',\n
`Repl_client_priv` enum('N','Y') character set utf8 NOT NULL default 'N',\n
`ssl_type` enum('','ANY','X509','SPECIFIED') character set utf8 NOT NULL default '',\n
`ssl_cipher` blob NOT NULL,\n
`x509_issuer` blob NOT NULL,\n
`x509_subject` blob NOT NULL,\n
`max_questions` int(11) unsigned NOT NULL default '0',\n
`max_updates` int(11) unsigned NOT NULL default '0',\n
`max_connections` int(11) unsigned NOT NULL default '0',\n
PRIMARY KEY  (`Host`,`User`)\n
) ENGINE=MyISAM DEFAULT CHARSET=utf8
COLLATE=utf8_bin COMMENT='Users and global privileges'
e' la colonna "max_questions"

evidentemente la tua versione tratta la variabile solo come globale. Prova ad utilizzare SET ..