Machine(s) not able to reboot

[Will Saxon]

Hello,

I have two HP Proliant DL360G3 servers which I recently upgraded from 5.2.1-R to 5.3-R. Since the upgrade, I am not able to cause the machines to shut down or reboot on their own. I always have to physically power them off and then back on. They are SMP machines and I am using ACPI. There are no other apparent problems although one machine did panic today and as a result I had to drive in and power cycle it. 

I saw some posts about this in mail archives, but they were very old. Has anyone else experienced this problem? What should I look for to fix this?

-Will