I am having issues refreshing my RuleBase. It works in some cases [small numbers of rules] and doesn't work in others. I am using the Guvnor to maintain rules and all my rules are in Excel decision table. To test, I created a simple package that contains 1 excel decision table which has 1 rule [row] in it. I ran my application. Then rebuilt the package in the Guvnor and my application refreshed the rule base correctly. Then in my actual application, I have other packages which contain many 100 rules if not 1000 rules all based on multiple excel based decision tables. If I run my application, then rebuild the package in the Guvnor, my application throws the exception. RuleAgent(Assembly) EXCEPTION (Fri Feb 26 12:02:32 EST 2010): java.lang.ClassCastException: org.drools.util.ObjectHashMap cannot be cast to org.drools.reteoo.BetaMemory. Stack trace should follow. org.drools.RuntimeDroolsException: java.lang.ClassCastException: org.drools.util.ObjectHashMap cannot be cast to org.drools.reteoo.BetaMemory It appears the problem occurs where there are many rules. Any ideas? This is going to be a major problem because the rules may need to be refreshed on a pretty regular basis and restarted the app each time is not an option. Thanks.