>  Does your kernel config include "options ACPI_DISABLE_ON_POWEROFF"?
>  If you can, could you try changing the option enabled or disabled
>  to see whether it makes any difference.

I have tried both with and without at various times, with no effect.  
It is currently enabled.

>  FYI, similar problem is reported in kern/27180, and I'd like to
>  know whether it's the same problem or not.

This is a different issue.  I can reboot with no trouble.

	--Ed