I just built installed the Drools Eclipse plug-in on a new development machine, and now whenever I load a new KnowledgeBuilder (KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();), the source of PackageBuilderConfiguration.class loads in a new tab with the following lines before the code: Class File Editor Source not found The JAR of this class file belongs to container 'Drools Library' which does not allow modifications to source attachments on its entries. The default 5.0.1 Drools Runtime jars are in the Drools Library path, just like on my previous development machine. Any thoughts? Ken Archer