I have taken the ear, created on a Windows box (java 1.6) and deployed it onto an Ububntu box (java 1.6) both on the same versions of JBoss (4.0.5)

I don't think I have altered the Windows install of JBoss at all.

I am a little confused in what class it can't find...

Please advise...

09:01:49,412 ERROR [[Faces Servlet]] Servlet.service() for servlet Faces Servlet threw exception
java.lang.NoClassDefFoundError: javax/el/ELContext
 at org.jboss.seam.util.UnifiedELValueBinding.<init>(UnifiedELValueBinding.java:18)
 at org.jboss.seam.security.Identity.evaluateExpression(Identity.java:506)
 at org.jboss.seam.security.Identity.checkRestriction(Identity.java:149)
 at org.jboss.seam.pages.Page.enter(Page.java:206)
 at org.jboss.seam.core.Pages.enterPage(Pages.java:276)
 at org.jboss.seam.jsf.AbstractSeamPhaseListener.enterPage(AbstractSeamPhaseListener.java:276)
 at org.jboss.seam.jsf.AbstractSeamPhaseListener.beforeRender(AbstractSeamPhaseListener.java:214)
 at org.jboss.seam.jsf.SeamPhaseListener.beforePhase(SeamPhaseListener.java:56)
 at org.apache.myfaces.lifecycle.PhaseListenerManager.informPhaseListenersBefore(PhaseListenerManager.java:70)
 at org.apache.myfaces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:373)
 at javax.faces.webapp.FacesServlet.service(FacesServlet.java:138)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
 at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
 at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
 at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175)
 at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
 at org.jboss.web.tomcat.tc5.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
 at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
 at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
 at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112)
 at java.lang.Thread.run(Thread.java:619