Integration

Hi, i have a problem with a random exception as:

java.lang.IllegalArgumentException: NamedQuery of name: ListingTestiSeo.findByLangZonaTipoZonaId not found.
at oracle.toplink.essentials.internal.ejb.cmp3.base.EJBQueryImpl.getDatabaseQuery(EJBQueryImpl.java:422)
at oracle.toplink.essentials.internal.ejb.cmp3.base.EJBQueryImpl.setParameterInternal(EJBQueryImpl.java:657)
at oracle.toplink.essentials.internal.ejb.cmp3.EJBQueryImpl.setParameter(EJBQueryImpl.java:202)
at it.agriturismo.listing.ListingTestiSeoBuilder.build(ListingTestiSeoBuilder.java:264)
at it.agriturismo.listing.ListingTestiSeoBuilder.getHeadTitle(ListingTestiSeoBuilder.java:309)
at org.apache.jsp.lazio.roma.ladispoli.index_jsp._jspService(index_jsp.java:363)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:427)
at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(AjpAprProtocol.java:384)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1527)
at java.lang.Thread.run(Unknown Source)

The strange thing is that actually happens in a random way and not systematically.

Systems configuration actually is:
Tomcat 6.0.20
Tomcat connector 1.2.28
MySQL Connector 5.0.8
Oracle TopLink Essentials - 2.0 (Build b58g-fcs (09/07/2007))
Java 1.6.0_14-b08
Windows 2003 R2 Datacenter

thanks in advance