I've upgraded Eclipse Platform from 3.0.2 version to 3.1
Now I can't start Eclipse; the log says:

!SESSION giu 03, 2006 22:17:02.790
---------------------------------------------
eclipse.buildId=M200409161125
java.version=1.4.2_06
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=it_IT

!ENTRY
initial@reference:file:c:/eclipse/eclipse/plugins/org.eclipse.core.runtime_3.1.1.jar/
0 0 giu 03, 2006 22:17:02.790
!MESSAGE FrameworkEvent.ERROR
!STACK 0
org.osgi.framework.BundleException: Exception in
org.eclipse.core.internal.runtime.PlatformActivator.start() of bundle
org.eclipse.core.runtime.
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:975)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:937)
    at
org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:421)
    at
org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:366)
    at
org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:999)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:577)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:488)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:273)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:444)
    at
org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:186)
    at
org.eclipse.osgi.framework.eventmgr.EventThread.run(EventThread.java:104)
Caused by: java.lang.NoClassDefFoundError:
org/eclipse/core/runtime/adaptor/FileManager
    at
org.eclipse.core.internal.runtime.InternalPlatform.initializeRuntimeFileManager(InternalPlatform.java:785)
    at
org.eclipse.core.internal.runtime.InternalPlatform.start(InternalPlatform.java:1086)
    at
org.eclipse.core.internal.runtime.PlatformActivator.startInternalPlatform(PlatformActivator.java:141)
    at
org.eclipse.core.internal.runtime.PlatformActivator.start(PlatformActivator.java:57)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:958)
    at java.security.AccessController.doPrivileged(Native Method)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:954)
    ... 10 more
Root exception:
java.lang.NoClassDefFoundError:
org/eclipse/core/runtime/adaptor/FileManager
    at
org.eclipse.core.internal.runtime.InternalPlatform.initializeRuntimeFileManager(InternalPlatform.java:785)
    at
org.eclipse.core.internal.runtime.InternalPlatform.start(InternalPlatform.java:1086)
    at
org.eclipse.core.internal.runtime.PlatformActivator.startInternalPlatform(PlatformActivator.java:141)
    at
org.eclipse.core.internal.runtime.PlatformActivator.start(PlatformActivator.java:57)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:958)
    at java.security.AccessController.doPrivileged(Native Method)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:954)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:937)
    at
org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:421)
    at
org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:366)
    at
org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:999)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:577)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:488)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:273)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:444)
    at
org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:186)
    at
org.eclipse.osgi.framework.eventmgr.EventThread.run(EventThread.java:104)

!ENTRY
initial@reference:file:c:/eclipse/eclipse/plugins/org.eclipse.update.configurator_3.1.0.jar/
0 0 giu 03, 2006 22:17:02.800
!MESSAGE FrameworkEvent.ERROR
!STACK 0
org.osgi.framework.BundleException: The activator
org.eclipse.update.internal.configurator.ConfigurationActivator for
bundle org.eclipse.update.configurator is invalid
    at
org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:158)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:933)
    at
org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:421)
    at
org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:366)
    at
org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:999)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:577)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:488)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:273)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:444)
    at
org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:186)
    at
org.eclipse.osgi.framework.eventmgr.EventThread.run(EventThread.java:104)
Caused by: java.lang.NoClassDefFoundError:
org/osgi/framework/BundleActivator
    at java.lang.ClassLoader.defineClass0(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:539)
    at
org.eclipse.osgi.framework.internal.defaultadaptor.DefaultClassLoader.defineClass(DefaultClassLoader.java:298)
    at
org.eclipse.core.runtime.adaptor.EclipseClassLoader.defineClass(EclipseClassLoader.java:223)
    at
org.eclipse.osgi.framework.internal.defaultadaptor.DefaultClassLoader.findClassImpl(DefaultClassLoader.java:281)
    at
org.eclipse.osgi.framework.internal.defaultadaptor.DefaultClassLoader.findClass(DefaultClassLoader.java:172)
    at
org.eclipse.osgi.framework.adaptor.core.AbstractClassLoader.findLocalClass(AbstractClassLoader.java:220)
    at
org.eclipse.core.runtime.adaptor.EclipseClassLoader.basicFindLocalClass(EclipseClassLoader.java:135)
    at
org.eclipse.core.runtime.adaptor.EclipseClassLoader.findLocalClass(EclipseClassLoader.java:73)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.findLocalClass(BundleLoader.java:371)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.findImportedClass(BundleLoader.java:794)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:395)
    at
org.eclipse.osgi.framework.adaptor.core.AbstractClassLoader.loadClass(AbstractClassLoader.java:93)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.loadClass(BundleLoader.java:307)
    at
org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:336)
    at
org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:151)
    ... 10 more
Root exception:
java.lang.NoClassDefFoundError: org/osgi/framework/BundleActivator
    at java.lang.ClassLoader.defineClass0(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:539)
    at
org.eclipse.osgi.framework.internal.defaultadaptor.DefaultClassLoader.defineClass(DefaultClassLoader.java:298)
    at
org.eclipse.core.runtime.adaptor.EclipseClassLoader.defineClass(EclipseClassLoader.java:223)
    at
org.eclipse.osgi.framework.internal.defaultadaptor.DefaultClassLoader.findClassImpl(DefaultClassLoader.java:281)
    at
org.eclipse.osgi.framework.internal.defaultadaptor.DefaultClassLoader.findClass(DefaultClassLoader.java:172)
    at
org.eclipse.osgi.framework.adaptor.core.AbstractClassLoader.findLocalClass(AbstractClassLoader.java:220)
    at
org.eclipse.core.runtime.adaptor.EclipseClassLoader.basicFindLocalClass(EclipseClassLoader.java:135)
    at
org.eclipse.core.runtime.adaptor.EclipseClassLoader.findLocalClass(EclipseClassLoader.java:73)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.findLocalClass(BundleLoader.java:371)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.findImportedClass(BundleLoader.java:794)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:395)
    at
org.eclipse.osgi.framework.adaptor.core.AbstractClassLoader.loadClass(AbstractClassLoader.java:93)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:235)
    at
org.eclipse.osgi.framework.internal.core.BundleLoader.loadClass(BundleLoader.java:307)
    at
org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:336)
    at
org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:151)
    at
org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:933)
    at
org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:421)
    at
org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:366)
    at
org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:999)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:577)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:488)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:273)
    at
org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:444)
    at
org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:186)
    at
org.eclipse.osgi.framework.eventmgr.EventThread.run(EventThread.java:104)

!ENTRY org.eclipse.osgi giu 03, 2006 22:17:02.810
!MESSAGE Startup error
!STACK 1
java.lang.IllegalStateException: Bundle
initial@reference:file:c:/eclipse/eclipse/plugins/org.eclipse.core.runtime_3.1.1.jar/
[249] is not active.
    at
org.eclipse.core.runtime.adaptor.EclipseStarter.ensureBundlesActive(EclipseStarter.java:303)
    at
org.eclipse.core.runtime.adaptor.EclipseStarter.startup(EclipseStarter.java:227)
    at
org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:127)
    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:324)
    at org.eclipse.core.launcher.Main.basicRun(Main.java:185)
    at org.eclipse.core.launcher.Main.run(Main.java:704)
    at org.eclipse.core.launcher.Main.main(Main.java:688)

!ENTRY org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.jdt.ui.examples.projects_3.0.0/
[226] was not resolved.
!SUBENTRY 1 org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.jdt.ui.examples.projects_3.0.1/
was picked instead.

!ENTRY org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.sdk.examples.source.win32.win32.x86_3.0.0/
[228] was not resolved.
!SUBENTRY 1 org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.sdk.examples.source.win32.win32.x86_3.0.1/
was picked instead.

!ENTRY org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.sdk.examples.source_3.0.0/
[230] was not resolved.
!SUBENTRY 1 org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.sdk.examples.source_3.0.1/
was picked instead.

!ENTRY org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.sdk.examples_3.0.0/
[232] was not resolved.
!SUBENTRY 1 org.eclipse.osgi giu 03, 2006 22:17:02.820
!MESSAGE Bundle
update@/C:/eclipse/plugins/comuni/eclipse/plugins/org.eclipse.sdk.examples_3.0.1/
was picked instead.

Thanks,

angelolar