Hi, I've created a new Drools dev setup with the latest version of the IDE (problem exists in Helios also), but having an issue running projects. Have stripped this down, and the problem exists even with a brand new project created with the Drools wizard. When running even the base DroolsTest in a default project I get the following error. Any ideas? --- java.lang.NoClassDefFoundError: org/eclipse/core/runtime/Plugin at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631) at java.lang.ClassLoader.defineClass(ClassLoader.java:615) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.access$000(URLClassLoader.java:58) at java.net.URLClassLoader$1.run(URLClassLoader.java:197) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at org.eclipse.jdt.internal.compiler.Compiler.initializeParser(Compiler.java:741) at org.eclipse.jdt.internal.compiler.Compiler.<init>(Compiler.java:295) at org.eclipse.jdt.internal.compiler.Compiler.<init>(Compiler.java:161) at org.drools.commons.jci.compilers.EclipseJavaCompiler.compile(EclipseJavaCompiler.java:356) at org.drools.commons.jci.compilers.AbstractJavaCompiler.compile(AbstractJavaCompiler.java:49) at org.drools.rule.builder.dialect.java.JavaDialect.compileAll(JavaDialect.java:368) at org.drools.compiler.DialectCompiletimeRegistry.compileAll(DialectCompiletimeRegistry.java:53) at org.drools.compiler.PackageRegistry.compileAll(PackageRegistry.java:70) at org.drools.compiler.PackageBuilder.compileAll(PackageBuilder.java:844) at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:801) at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:385) at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:563) at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:35) at com.sample.DroolsTest.readKnowledgeBase(DroolsTest.java:40) at com.sample.DroolsTest.main(DroolsTest.java:23) Caused by: java.lang.ClassNotFoundException: org.eclipse.core.runtime.Plugin at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) ... 27 more -- -- View this message in context: http://drools.46999.n3.nabble.com/NoClassDefFoundError-org-eclipse-core-r... Sent from the Drools: User forum mailing list archive at Nabble.com.