Creating a new JPA project and configuring it to use Hibernate and Tomcat 6 when I try to open the persistence.xml file I get the error shown below.
Using Dali ver. 2.0 everything works fine.

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ERROR GENERATED TRYING TO OPEN PERSISTENCE.XML

eclipse.buildId=M20080911-1700
java.version=1.6.0_10
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=it_IT
Command-line arguments: -os win32 -ws win32 -arch x86

Error
Mon Jan 26 15:18:39 CET 2009
Problems occurred when invoking code from plug-in: "org.eclipse.jface".

java.lang.InstantiationError: org.eclipse.jpt.ui.internal.persistence.details.PersistenceUnitGeneralComposite
at org.jboss.tools.hibernate.jpt.ui.internal.platform.HibernateUiFactory.createPersistenceUnitComposites(HibernateUiFactory.java:27)
at org.eclipse.jpt.ui.internal.editors.PersistenceEditor.addPersistenceUnitPages(PersistenceEditor.java:130)
at org.eclipse.jpt.ui.internal.editors.PersistenceEditor.addPages(PersistenceEditor.java:109)
at org.eclipse.ui.forms.editor.FormEditor.createPages(FormEditor.java:146)
at org.eclipse.ui.part.MultiPageEditorPart.createPartControl(MultiPageEditorPart.java:310)
at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:661)
at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:428)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:594)
at org.eclipse.ui.internal.EditorReference.getEditor(EditorReference.java:266)
at org.eclipse.ui.internal.WorkbenchPage.makeActiveEditor(WorkbenchPage.java:1246)
at org.eclipse.ui.internal.WorkbenchPage.updateActivePart(WorkbenchPage.java:1204)
at org.eclipse.ui.internal.WorkbenchPage.partAdded(WorkbenchPage.java:1665)
at org.eclipse.ui.internal.EditorAreaHelper.addEditor(EditorAreaHelper.java:210)
at org.eclipse.ui.internal.EditorManager.createEditorTab(EditorManager.java:779)
at org.eclipse.ui.internal.EditorManager.openEditorFromDescriptor(EditorManager.java:678)
at org.eclipse.ui.internal.EditorManager.openEditor(EditorManager.java:639)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2817)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2729)
at org.eclipse.ui.internal.WorkbenchPage.access$11(WorkbenchPage.java:2721)
at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2673)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2668)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2652)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2635)
at org.eclipse.jpt.ui.internal.actions.OpenJpaResourceAction.openEditor(OpenJpaResourceAction.java:92)
at org.eclipse.jpt.ui.internal.actions.OpenJpaResourceAction.run(OpenJpaResourceAction.java:73)
at org.eclipse.ui.actions.RetargetAction.run(RetargetAction.java:221)
at org.eclipse.ui.internal.navigator.CommonNavigatorManager$3.open(CommonNavigatorManager.java:184)
at org.eclipse.jface.viewers.StructuredViewer$2.run(StructuredViewer.java:820)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37)
at org.eclipse.core.runtime.Platform.run(Platform.java:880)
at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48)
at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
at org.eclipse.jface.viewers.StructuredViewer.fireOpen(StructuredViewer.java:818)
at org.eclipse.jface.viewers.StructuredViewer.handleOpen(StructuredViewer.java:1079)
at org.eclipse.ui.navigator.CommonViewer.handleOpen(CommonViewer.java:372)
at org.eclipse.jface.viewers.StructuredViewer$6.handleOpen(StructuredViewer.java:1183)
at org.eclipse.jface.util.OpenStrategy.fireOpenEvent(OpenStrategy.java:263)
at org.eclipse.jface.util.OpenStrategy.access$2(OpenStrategy.java:257)
at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:297)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3823)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3422)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2382)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2346)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2198)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:493)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:488)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:193)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:386)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504)
at org.eclipse.equinox.launcher.Main.run(Main.java:1236)