Singleton error while launching Test Server

Hi,
I've some problem with development environment setup for RTC 3.0 release. I've followed RTC SDK topic and I successfully create test DB for either jts and ccm and run them.
Some day after I retry to start the server test and then I get this error:

[ERROR] 2011-04-05 17:28:03.578 - FrameworkManager: An error event has occurred involving the bundle "org.eclipse.core.resources_3.5.2.R35x_v20091203-1235 [196]".

org.osgi.framework.BundleException: The bundle could not be resolved. Reason: Another singleton version selected: org.eclipse.core.resources_3.5.3.R35x_v20100928-0452

	at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolverError(AbstractBundle.java:1313)

	at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolutionFailureException(AbstractBundle.java:1297)

	at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:309)

	at org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:370)

	at org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:1068)

	at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:557)

	at org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:464)

	at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:248)

	at org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:445)

	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:227)

	at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:337)

Do you have some idea on how to resolve it?

Thanks,
Michele