Error in the authentication of a web system

I'm learning next to a tutorial to develop a petshop system and am getting the following Hibernate error:

  

Hibernate: select client0_.idClient idClient2_2_, client0_.email as email3_2_, client0_.name the_name_2_, client0_.password the password5_2_, client0_.type as type1_2_ from Client client0_ left outer join PF client0_1_ on client0_.idClient = client0_1_. idClient left outer join PJ client0_2_ on client0_.idClient = client0_2_.idClient where client0_.email =? and cliente0_.senha =?   Authentication Error

Authenticate method (from the ClientMTD class):

public static Autenticavel autenticar(String usuario, String senha) {
    Session session = HibernateUtil.getInstance();
    Transaction tx = null;
    Cliente p = null;
    try {
        Query q;
        tx = session.beginTransaction();
        q = session.createQuery("FROM Cliente as p where p.email=:usuario and p.senha=:senha");
        q.setParameter("usuario", usuario);
        q.setParameter("senha", senha);
        List resultados = q.list();
        if (resultados.size() > 0) {
            p = (Cliente) resultados.get(0);
        }
        return p;
    } catch (Exception e) {
        tx.rollback();
        e.printStackTrace();
        return p;
    } finally {
        session.close();
    }
}

Authentication.java:

package br.com.diego.controle;

public interface Autenticavel {

public Autenticavel autenticar(String usuario, String senha);

public boolean existe(String usuario);
}

TestingHibernate.java:

public class TestandoHibernate {

public static void main(String[] args) {

    GerarTabelas();
    if (autenticar("[email protected]", "root") != null) {
        System.out.println("Usuário autenticado");
    } else {
        System.out.println("Erro na autenticação");
    }
    try {
        persistindo();
    } catch (Exception ex) {
        JOptionPane.showMessageDialog(null, "Erro" + ex.getMessage());
    }
}

 public static Autenticavel autenticar(String usuario, String senha) {
    return new PF().autenticar(usuario, senha);
}

private static void persistindo() throws Exception {
    PF pf = new PF();
    pf.setNome("Diego Juarez");
    pf.setEmail("[email protected]");
    pf.setSenha("root");
    DocReceita CPF = new CPF(" 122. 379. 567-58 ");
    pf.setDocReceita(CPF);
    CPF.setCliente(pf);

    if (pf.existe(CPF) == true) {
        throw new RuntimeException("<br><center><font face='verdana' color='red'   size='2'><br />já existe usuário cadastrado com o CPF ou CNPJ informado</font></center><br>");
    }

    Endereco end = new Endereco();
    end.setBairro("Centro");
    end.setCep("28610175");
    end.setCidade("Nova Friburgo");
    end.setLograd("Pca Presidente Getulio Vargas 220");
    end.setNumero("402");
    end.setUf("RJ");
    end.setCliente(pf);

    Collection<Endereco> e = new ArrayList<Endereco>();
    e.add(end);
    pf.setEndereco(e);

    Telefone t = new Telefone();
    t.setCodArea(21);
    t.setNumero("988336760");
    t.setCliente(pf);

    Collection<Telefone> tel = new ArrayList<Telefone>();
    tel.add(t);
    pf.setTelefone(tel);

    Pet a = new Cachorro();
    Date d = new Date(2010, 04, 26);
    a.setDataNascimento(d);
    a.setNome("Rex");
    a.setRaca("Bulldog");
    a.setSexo('M');
    a.setObs("Peida muito!");
    a.setCliente(pf);

    Servico s = new Consulta();
    s.setData(new Date());
    s.setDescricao("Problema de peso");
    s.setValor(20);
    s.setPet(a);

    Collection<Servico> serv = new ArrayList<Servico>();
    serv.add(s);
    a.setServico(serv);

    Collection<Pet> peti = new ArrayList<Pet>();
    peti.add(a);
    pf.setPet(peti);

    PF.salvar(pf);
}    
}

Can anyone help me find the error? Thank you in advance!

hibernate.cfg.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
 <!-- Database connection settings -->

    <property name="connection.url">jdbc:mysql://localhost:3306/petshop1</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="connection.username">root</property>
    <property name="connection.password">6452software</property>

    <!-- JDBC connection pool (use the built-in) -->
    <property name="connection.pool_size">10</property>

    <!-- SQL dialect -->
    <property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>

    <!-- Enable Hibernate's automatic session context management -->
    <property name="current_session_context_class">thread</property>


    <!-- Echo all executed SQL to stdout -->
    <property name="show_sql">true</property>

    <!-- Drop and re-create the database schema on startup -->
    <property name="hbm2ddl.auto">update</property>

<mapping class="br.com.diego.controle.Cliente"/>
<mapping class="br.com.diego.controle.PF"/>
<mapping class="br.com.diego.controle.PJ"/>
<mapping class="br.com.diego.controle.DocReceita"/>
<mapping class="br.com.diego.controle.CPF"/>
<mapping class="br.com.diego.controle.CNPJ"/>
<mapping class="br.com.diego.controle.Endereco"/>
<mapping class="br.com.diego.controle.Pet"/>
<mapping class="br.com.diego.controle.Cachorro"/>
<mapping class="br.com.diego.controle.Gato"/>
<mapping class="br.com.diego.controle.Servico"/>
<mapping class="br.com.diego.controle.Banho"/>
<mapping class="br.com.diego.controle.Consulta"/>
<mapping class="br.com.diego.controle.Telefone"/>
<mapping class="br.com.diego.controle.Tosa"/>
<mapping class="br.com.diego.controle.Vacina"/>
</session-factory>
</hibernate-configuration>