When I try to debug my standard Java application (or a JUnit test) I get the following NPE (I also tried it with an empty userdir, no difference). There is no message in the IDE's log file

Plattform: Windows XP
JDK: 1.6.0_16
The project is a normal Java application with no dependencies.

Here is the stacktrace as shown in the output window:

init:
Deleting: C:\Projects\sqlworkbench\nb67project\build\built-jar.properties
deps-jar:
Updating property file: C:\Projects\sqlworkbench\nb67project\build\built-jar.properties
compile:
C:\Projects\sqlworkbench\nb67project\nbproject\build-impl.xml:576: The following error occurred while executing this line:
C:\Projects\sqlworkbench\nb67project\nbproject\build-impl.xml:279: 
java.lang.NullPointerException
        at org.netbeans.modules.debugger.jpda.ant.JPDAStart.execute(JPDAStart.java:222)
        at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
        at sun.reflect.GeneratedMethodAccessor60.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
        at org.apache.tools.ant.Task.perform(Task.java:348)
        at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:62)
        at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
        at sun.reflect.GeneratedMethodAccessor60.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
        at org.apache.tools.ant.Task.perform(Task.java:348)
        at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:394)
        at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
        at sun.reflect.GeneratedMethodAccessor60.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
        at org.apache.tools.ant.Task.perform(Task.java:348)
        at org.apache.tools.ant.Target.execute(Target.java:357)
        at org.apache.tools.ant.Target.performTasks(Target.java:385)
        at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1337)
        at org.apache.tools.ant.Project.executeTarget(Project.java:1306)
        at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
        at org.apache.tools.ant.Project.executeTargets(Project.java:1189)
        at org.apache.tools.ant.module.bridge.impl.BridgeImpl.run(BridgeImpl.java:278)
        at org.apache.tools.ant.module.run.TargetExecutor.run(TargetExecutor.java:498)
        at org.netbeans.core.execution.RunClassThread.run(RunClassThread.java:151)
BUILD FAILED (total time: 1 second)