Doh!  It seems that certain Cisco IPS systems can spit up a core file and go all brain-dead within 24 hours after a transition to or from daylight-savings-time.  You'll need a COO password to view the Cisco bulletin found here.

Update: If you don't have a COO account, you can still see the bulletin here. (Thanks, Tim!)

Clarification: The above probably implies that the IPS is completely dead.  In reality, monitoring and alarming remain functional.  The command-line interface (CLI) is what is curled up in the corner with its paws pointing skyward.