Why does HP server reboot or shutdown unexpectedly?

Issue

• Occasionally a HP server hangs and reboots itself automatically without a log that defines the cause of the reboot.
• Sar report did not show any unusual resource utilization prior to reboot.
• iLO IML log shows following messages :

 Severity Class Last Update Initial Update Count Description  
 Critical ASR 05/25/2011 20:39 05/25/2011 20:39 1 ASR Detected by System ROM  
 Repaired Network 04/28/2011 20:05 09/18/2010 01:04 13 Network Adapters Redundancy Reduced (Slot 2, Port 13)  
 Repaired Network 04/28/2011 20:13 08/19/2010 20:43 6 Network Adapters Redundancy Reduced (Slot 0, Port 13)  
 Informational Rack Infrastructure 07/16/2009 20:53 07/16/2009 20:53 1 Server Blade Enclosure Rack Name Changed (Enclosure Serial Number USE916LNJE)  
 Caution POST Message 11/04/2008 05:08 11/04/2008 05:08 1 POST Error: 1785-Drive Array not Configured  
 Caution POST Message 11/04/2008 04:54 11/04/2008 04:54 1 POST Error: 1785-Drive Array not Configured  
 Caution POST Message 11/02/2008 00:01 11/02/2008 00:01 1 POST Error: 1785-Drive Array not Configured