Reboot fails: 5 beeps and a freeze

[Billy Newsom]

My issue: Why does FreeBSD 5.3 not reboot?  It basically locks up when I 
  perform a reboot.  The same thing happens if I halt and then press any 
key to reboot.

Here's sort of what I see on the local terminal (some snips):

Uptime: blah....
Rebooting...
cpu_reset called on CPU#0
cpu_reset: Stopping other CPUs
<Stuck Block cursor>

...and that's all I ever see.  But while this is being printed to the 
screen, I get five beeps.  I don't remember that many beeps in FreeBSD 4.x.

BEEP, beep beep beep, BEEP

I don't know how long I've waited for the system to reboot, but so far 
it hasn't.  The system is a dual-processor Pentium Pro with an APM BIOS 
and no ACPI.  This machine rebooted fine when it ran FreeBSD 4.7.

Has the code changed for the cpu_reset function recently that would 
cause this regression?

Thanks,
Billy