Erro Mysql + Hibernate

Pessoal tenho um site rodando usando o hibernate 2 + mysql.
É feita apenas uma consulta para verificar o usuario.
A consulta é voltada normalmente, mas em determinado momento dá um erro e a consulta não volta nada parando o site.
Erro:
com.mysql.jdbc.CommunicationsException
java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1913)
Abaixo coloquei o erro mais detalhado.
Procurei e achei que poderia ser o drive do mysql.
Atualizei o drive para o mysql-connector-java-5.0.3-bin.jar,
mas mesmo assim o erro continou.
Também mudei nas configurações do hibernate deixando assim:

<property name="connection.driver_class">org.gjt.mm.mysql.Driver</property>        
    <property name="connection.url">jdbc:mysql://web:3306/teste</property>
    <property name="connection.autoReconnect">true</property>
    <property name="connection.relaxAutoCommit">true</property>              
    <property name="connection.username">username</property>
    <property name="connection.password">senha</property>
    <property name="connection.pool.size">0</property>
    <property name="show_sql">true</property>
    <property name="dialect">net.sf.hibernate.dialect.MySQLDialect</property>        
    <property name="connection.maxIdle">10</property>
    <property name="connection.maxActive">10</property>
    <property name="connection.maxWait">20000</property>
    <property name="connection.whenExhaustedAction">1</property>
    <property name="connection.autoReconnectForPools">true</property>        

Tenho outros sites com as mesmas configurações e estes outros sites não dão esse erro.
O que será que pode estar acontecendo?

Erro detalhado:

** BEGIN NESTED EXCEPTION **

com.mysql.jdbc.CommunicationsException
MESSAGE: Communications link failure due to underlying exception:

** BEGIN NESTED EXCEPTION **

java.io.EOFException

STACKTRACE:

java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1913)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2304)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2803)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1665)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3124)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1149)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1262)
at net.sf.hibernate.impl.BatcherImpl.getResultSet(BatcherImpl.java:83)
at net.sf.hibernate.loader.Loader.getResultSet(Loader.java:790)
at net.sf.hibernate.hql.QueryTranslator.iterate(QueryTranslator.java:842)
at net.sf.hibernate.impl.SessionImpl.iterate(SessionImpl.java:1538)
at net.sf.hibernate.impl.QueryImpl.iterate(QueryImpl.java:33)
at br.com.valoriza.sitecursos.persistencia.PersistenciaUsuarioCurso.recupera(PersistenciaUsuarioCurso.java:239)
at br.com.valoriza.sitecursos.jsp.usuario.GerenciaUsuariosCurso.autenticaUsuario(GerenciaUsuariosCurso.java:122)
at br.com.valoriza.jsp.usuario.GerenciaUsuarios.verificaUsuario(Unknown Source)
at br.com.valoriza.sitecursos.jsp.usuario.AutenticaUsuario.executa(AutenticaUsuario.java:37)
at br.com.valoriza.jsp.mvc.controle.ServletControleFormulario.encaminha(ServletControleFormulario.java:110)
at br.com.valoriza.jsp.mvc.controle.ServletControle.doPost(ServletControle.java:31)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:535)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:300)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:374)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:743)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:675)
at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:866)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Thread.java:595)

** END NESTED EXCEPTION **

Last packet sent to the server was 3 ms ago.

está fechando a conexão após as consultas?