When running "Building a Java Desktop Database Application" tutorial, I had the following messages. The solution (and the problem) was the 'é' in the Path where the project was. So the Toplink problem es when there is these kind of special characters in the Path.
Regards.
Andrés.


init:
deps-jar:
Copying 23 files to C:\Documents and Settings\Andrés\Mis documentos\NetBeansProjects\Car\build\classes
compile:
run:
01/11/2007 23:01:49 org.jdesktop.application.Application$1 run
GRAVE: Application class car.CarApp failed to launch
javax.persistence.PersistenceException: No Persistence provider for EntityManager named heladeriaPU:  The following providers:
oracle.toplink.essentials.PersistenceProvider
oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider
Returned null to createEntityManagerFactory.

        at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:154)
        at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
        at car.CarView.initComponents(CarView.java:270)
        at car.CarView.<init>(CarView.java:34)
        at car.CarApp.startup(CarApp.java:19)
        at org.jdesktop.application.Application$1.run(Application.java:174)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
Exception in thread "AWT-EventQueue-0" java.lang.Error: Application class car.CarApp failed to launch
        at org.jdesktop.application.Application$1.run(Application.java:180)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
Caused by: javax.persistence.PersistenceException: No Persistence provider for EntityManager named heladeriaPU:  The following providers:
oracle.toplink.essentials.PersistenceProvider
oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider
Returned null to createEntityManagerFactory.

        at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:154)
        at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
        at car.CarView.initComponents(CarView.java:270)
        at car.CarView.<init>(CarView.java:34)
        at car.CarApp.startup(CarApp.java:19)
        at org.jdesktop.application.Application$1.run(Application.java:174)
        ... 8 more
BUILD SUCCESSFUL (total time: 4 seconds)