I'm suddenly getting the following exception at JBoss 5.1.2 startup:

ERROR [org.apache.catalina.startup.Catalina]::start(577) - Catalina.start:
LifecycleException:  Caught exception stopping JBossCacheSSOClusterManager:  org.jboss.cache.CacheException: java.lang.reflect.InvocationTargetException
    at org.jboss.web.tomcat.service.sso.ClusteredSingleSignOn.start(ClusteredSingleSignOn.java:435)
    at org.apache.catalina.core.StandardPipeline.start(StandardPipeline.java:235)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1061)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1056)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
    at org.apache.catalina.core.StandardService.start(StandardService.java:523)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:736)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:575)
    at org.jboss.web.tomcat.service.deployers.TomcatService.startService(TomcatService.java:316)
    at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:376)
  

While trying to login I get the following exception:

 ERROR [org.jboss.web.tomcat.service.sso.jbc.JBossCacheSSOClusterManager]::lookup(410) - caught exception looking up SSOCredentials for SSO id 3B3EEBF9B7F26111A5F91FC8A0C08CE6
org.jboss.cache.invocation.CacheNotReadyException: Cache not in a valid STARTED state!  Cache state is FAILED
    at org.jboss.cache.invocation.CacheInvocationDelegate.cacheStatusCheck(CacheInvocationDelegate.java:695)
    at org.jboss.cache.invocation.CacheInvocationDelegate.get(CacheInvocationDelegate.java:442)
    at org.jboss.ha.cachemanager.CacheManagerManagedCache.get(CacheManagerManagedCache.java:193)
    at org.jboss.web.tomcat.service.sso.jbc.JBossCacheSSOClusterManager.getFromTreeCache(JBossCacheSSOClusterManager.java:873)
 
ERROR [org.apache.catalina.connector.CoyoteAdapter]::service(353) - An exception or error occurred in the container during the request processing
java.lang.IllegalStateException: Uncomment the dependency on CachedConnectionManager in META-INF/jboss-service.xml of jbossweb-tomcatxxx.sar
    at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:151)
    at org.jboss.web.tomcat.service.sso.ClusteredSingleSignOn.invoke(ClusteredSingleSignOn.java:711)
    at org.apache.catalina.valves.RequestDumperValve.invoke(RequestDumperValve.java:151)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

Does someone have a glue what's going on here?