Error with IntelliJ integration

I just installed build #798, then I installed IntelliJ Idea integration plugin and when I started IntelliJ, I got the following error message:

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:77)

    at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.a(ComponentManagerImpl.java:48)

    at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.access$100(ComponentManagerImpl.java:4)

    at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:89)

    at com.intellij.openapi.components.impl.ComponentManagerImpl.initComponents(ComponentManagerImpl.java:129)

    at com.intellij.openapi.components.impl.ComponentManagerImpl.init(ComponentManagerImpl.java:67)

    at com.intellij.openapi.project.impl.ProjectImpl.init(ProjectImpl.java:28)

    at com.intellij.openapi.project.impl.ProjectManagerImpl.getDefaultProject(ProjectManagerImpl.java:79)

    at com.intellij.ide.impl.ProjectUtil$1.run(ProjectUtil.java:3)

    at com.intellij.openapi.progress.impl.ProgressManagerImpl$2.run(ProgressManagerImpl.java:11)

    at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:50)

    at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcess(ProgressManagerImpl.java:54)

    at com.intellij.openapi.application.impl.ApplicationImpl$7$1.run(ApplicationImpl.java:9)

    at com.intellij.openapi.application.impl.ApplicationImpl$5.run(ApplicationImpl.java:9)

    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)

    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)

    at java.util.concurrent.FutureTask.run(FutureTask.java:123)

    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)

    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)

    at java.lang.Thread.run(Thread.java:613)

    at com.intellij.openapi.application.impl.ApplicationImpl$1$1.run(ApplicationImpl.java:7)

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:67)

    ... 20 more

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:67)

    at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.a(ComponentManagerImpl.java:48)

    at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentsRegistry.access$100(ComponentManagerImpl.java:4)

    at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:89)

    at com.intellij.openapi.components.impl.ComponentManagerImpl.initComponents(ComponentManagerImpl.java:129)

    at com.intellij.openapi.components.impl.ComponentManagerImpl.init(ComponentManagerImpl.java:67)

    at com.intellij.openapi.project.impl.ProjectImpl.init(ProjectImpl.java:28)

    at com.intellij.openapi.project.impl.ProjectManagerImpl.getDefaultProject(ProjectManagerImpl.java:79)

    at com.intellij.ide.impl.ProjectUtil$1.run(ProjectUtil.java:3)

    at com.intellij.openapi.progress.impl.ProgressManagerImpl$2.run(ProgressManagerImpl.java:11)

    at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:50)

    at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcess(ProgressManagerImpl.java:54)

    at com.intellij.openapi.application.impl.ApplicationImpl$7$1.run(ApplicationImpl.java:9)

    at com.intellij.openapi.application.impl.ApplicationImpl$5.run(ApplicationImpl.java:9)

    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)

    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)

    at java.util.concurrent.FutureTask.run(FutureTask.java:123)

    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)

    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)

    at java.lang.Thread.run(Thread.java:613)

    at com.intellij.openapi.application.impl.ApplicationImpl$1$1.run(ApplicationImpl.java:7)

What could this be?