Autopackage class version error during startup

Apple Macbook pro - jdk 1.5.0_13

Any help would be good.

Bad version number in .class file
com.intellij.diagnostic.PluginException: Bad version number in .class file
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.a(ComponentManagerImpl.java:2)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.a(ComponentManagerImpl.java:50)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.access$100(ComponentManagerImpl.java:29)
at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:90)
at com.intellij.openapi.components.impl.ComponentManagerImpl.initComponents(ComponentManagerImpl.java:162)
at com.intellij.openapi.components.impl.ComponentManagerImpl.init(ComponentManagerImpl.java:74)
at com.intellij.openapi.module.impl.ModuleManagerImpl$ModuleModelImpl.a(ModuleManagerImpl.java:43)
at com.intellij.openapi.module.impl.ModuleManagerImpl$ModuleModelImpl.b(ModuleManagerImpl.java:65)
at com.intellij.openapi.module.impl.ModuleManagerImpl$ModuleModelImpl.access$500(ModuleManagerImpl.java:143)
at com.intellij.openapi.module.impl.ModuleManagerImpl$2.run(ModuleManagerImpl.java:16)
at com.intellij.openapi.application.impl.LaterInvocator$1.run(LaterInvocator.java:1)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:19)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at com.intellij.ide.IdeEventQueue.c(IdeEventQueue.java:131)
at com.intellij.ide.IdeEventQueue.b(IdeEventQueue.java:132)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:136)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:180)
at java.awt.Dialog$1.run(Dialog.java:535)
at java.awt.Dialog$2.run(Dialog.java:563)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.Dialog.show(Dialog.java:561)
at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl$MyDialog.show(DialogWrapperPeerImpl.java:4)
at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl.show(DialogWrapperPeerImpl.java:92)
at com.intellij.openapi.ui.DialogWrapper.show(DialogWrapper.java:813)
at com.intellij.openapi.progress.util.ProgressWindow$MyDialog.show(ProgressWindow.java:1)
at com.intellij.openapi.progress.util.ProgressWindow.showDialog(ProgressWindow.java:70)
at com.intellij.openapi.progress.util.ProgressWindow$1$1.run(ProgressWindow.java:3)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:19)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at com.intellij.ide.IdeEventQueue.c(IdeEventQueue.java:131)
at com.intellij.ide.IdeEventQueue.b(IdeEventQueue.java:132)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:136)
at com.intellij.ide.IdeEventQueue.pumpEventsForHierarchy(IdeEventQueue.java:99)
at com.intellij.openapi.progress.util.ProgressWindow.startBlocking(ProgressWindow.java:83)
at com.intellij.openapi.application.impl.ApplicationImpl.runProcessWithProgressSynchronously(ApplicationImpl.java:29)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcessWithProgressSynchronously(ProgressManagerImpl.java:86)
at com.intellij.openapi.project.impl.ProjectManagerImpl.loadAndOpenProject(ProjectManagerImpl.java:31)
at com.intellij.openapi.project.impl.ProjectManagerImpl.loadAndOpenProject(ProjectManagerImpl.java:237)
at com.intellij.ide.impl.ProjectUtil.openProject(ProjectUtil.java:115)
at com.intellij.idea.IdeaApplication.b(IdeaApplication.java:36)
at com.intellij.idea.IdeaApplication.access$400(IdeaApplication.java:60)
at com.intellij.idea.IdeaApplication$IdeStarter$3.run(IdeaApplication.java:4)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:19)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at com.intellij.ide.IdeEventQueue.c(IdeEventQueue.java:131)
at com.intellij.ide.IdeEventQueue.b(IdeEventQueue.java:132)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:136)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
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:675)
at java.lang.ClassLoader.defineClass(ClassLoader.java:520)
at com.intellij.util.lang.UrlClassLoader._defineClass(UrlClassLoader.java:132)
at com.intellij.util.lang.UrlClassLoader.defineClass(UrlClassLoader.java:128)
at com.intellij.util.lang.UrlClassLoader._findClass(UrlClassLoader.java:104)
at com.intellij.ide.plugins.cl.PluginClassLoader.loadClassInsideSelf(PluginClassLoader.java:75)
at com.intellij.ide.plugins.cl.PluginClassLoader._loadClass(PluginClassLoader.java:42)
at com.intellij.util.lang.UrlClassLoader.loadClass(UrlClassLoader.java:80)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:374)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:242)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.a(ComponentManagerImpl.java:75)
... 56 more