org.jboss.seam.navigation.SafeActions is application scoped component and as it is not ready for replication. SafeActions is used for checking of EL expresions which can be invoked from actionMethod URL parameter, s:link etc..
While on classic one node server it works fine, but if you are on multi-node cluster and expects correct fail-over while you are invoking actionMethod on backup server node, SafeActions is not replicated to other server node.

We need a distributed cache storage for this SafeActions.