I have the following error using ubuntu 10.04
Eclipse
Version: 3.5.2
Build id: M20100211-1343

HTTP ERROR 500

Problem accessing /help/index.jsp. Reason:

    Bad version number in .class file

Caused by:

java.lang.UnsupportedClassVersionError: Bad version number in .class file
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.defineClass(DefaultClassLoader.java:183)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.defineClass(ClasspathManager.java:576)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findClassImpl(ClasspathManager.java:546)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClassImpl(ClasspathManager.java:477)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass_LockClassLoader(ClasspathManager.java:465)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:445)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:211)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:381)
	at org.eclipse.osgi.internal.loader.SingleSourcePackage.loadClass(SingleSourcePackage.java:33)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:445)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:410)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:398)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:105)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
	at org.eclipse.equinox.jsp.jasper.JspServlet.<init>(JspServlet.java:65)
	at org.eclipse.equinox.jsp.jasper.registry.JSPFactory.create(JSPFactory.java:56)
	at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:262)
	at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:51)
	at org.eclipse.equinox.http.registry.internal.ServletManager$ServletWrapper.initializeDelegate(ServletManager.java:194)
	at org.eclipse.equinox.http.registry.internal.ServletManager$ServletWrapper.service(ServletManager.java:179)
	at org.eclipse.equinox.http.servlet.internal.ServletRegistration.handleRequest(ServletRegistration.java:90)
	at org.eclipse.equinox.http.servlet.internal.ProxyServlet.processAlias(ProxyServlet.java:111)
	at org.eclipse.equinox.http.servlet.internal.ProxyServlet.service(ProxyServlet.java:75)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.eclipse.equinox.http.jetty.internal.HttpServerManager$InternalHttpServiceServlet.service(HttpServerManager.java:318)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:390)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.Server.handle(Server.java:326)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
	at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
	at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
	at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
	at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)