I know there have been a million posts about these kind of errors but mine seems to happen intermittently which is still quite unacceptable for a production environment. This happens about half a dozen times a day. Where do I even begin to look? My setup: Box A: IP A.A.A.A with Jboss 4.2.1 on Linux Box B: IP B.B.B.B with Tomcat 5.5.25 on Linux Tomcat on Box B is started with: -Djava.naming.provider.url=jnp://box1:1099 -Djava.naming.factory.initial=org.jnp.interfaces.NamingContextFactory -Djava.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces and in /etc/hosts box1 is mapped to A.A.A.A The details of the exception: Tools::lookup() -> Could not discover class <MYCLASS> | javax.naming.CommunicationException [Root exception is java.rmi.ConnectException: Connection refused to host: A.A.A.A; nested exception is: | java.net.ConnectException: Connection timed out] | at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:724) | at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:589) | at javax.naming.InitialContext.lookup(InitialContext.java:351) | at Tools.lookup(Tools.java:17) | ... Many thanks for any ideas! (pls don't mention firewalls. it's not that!) dok P.S. Tools::lookup() does a simple InitalContext.lookup(classname). View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4131703#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...