NPE after connecting a project with the sonar server

eclipse.buildId=M20110210-1200
java.version=1.6.0_24
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=de_DE
Command-line arguments:  -os win32 -ws win32 -arch x86


Error
Thu Apr 07 10:19:35 CEST 2011
An error occurred while traversing resources.

java.lang.NullPointerException
at org.sonar.ide.eclipse.internal.jdt.JavaElementsAdapterFactory.getAdapter(JavaElementsAdapterFactory.java:87)
at org.eclipse.core.internal.runtime.AdapterManager.getAdapter(AdapterManager.java:326)
at org.eclipse.core.internal.runtime.AdapterManager.loadAdapter(AdapterManager.java:356)
at org.sonar.ide.eclipse.ui.util.PlatformUtils.adapt(PlatformUtils.java:56)
at org.sonar.ide.eclipse.internal.ui.jobs.RefreshAllViolationsJob.visit(RefreshAllViolationsJob.java:85)
at org.eclipse.core.internal.resources.Resource$2.visit(Resource.java:112)
at org.eclipse.core.internal.resources.Resource$1.visitElement(Resource.java:64)
at org.eclipse.core.internal.watson.ElementTreeIterator.doIteration(ElementTreeIterator.java:82)
at org.eclipse.core.internal.watson.ElementTreeIterator.iterate(ElementTreeIterator.java:127)
at org.eclipse.core.internal.resources.Resource.accept(Resource.java:74)
at org.eclipse.core.internal.resources.Resource.accept(Resource.java:110)
at org.eclipse.core.internal.resources.Resource.accept(Resource.java:94)
at org.sonar.ide.eclipse.internal.ui.jobs.AbstractRefreshModelJob.run(AbstractRefreshModelJob.java:71)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)