This DisplayString is the name of the specific critical device or check that ClusterXL has flagged as a problem, keyed by haProblemIndex, such as Synchronization or a named security daemon. Because ClusterXL's decision to demote a member to standby is driven by these named critical device reports, this field tells the admin precisely which subsystem triggered the concern rather than just that something is wrong. A haProblemName of fwd (the Check Point firewall daemon) being flagged would point at a process-level failure rather than a network link problem.