Frequent NMI warnings

[Peter Risdon]

Hi,

$ uname -a
FreeBSD xxxxxxxx.xxxxxxxxxxxxxxxx.com 9.1-RELEASE FreeBSD 9.1-RELEASE #0
r243825: Tue Dec  4 09:23:10 UTC 2012
root at farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC
 amd64

I'm getting a lot of these errors in the logs:

+NMI ISA 30, EISA 0
+NMI ISA 30, EISA 0
+NMI ... going to debugger
+NMI ISA 30, EISA 0
+NMI ... going to debugger
+NMI ... going to debugger
+NMI ISA 30, EISA 0
+NMI ISA 30, EISA 0
+NMI ... going to debugger
+NMI ... going to debugger
+NMI ISA 30, EISA 0
+NMI ISA 30, EISA 0
+NMI ... going to debugger
+NMI ... going to debugger
+NMI ISA 30, EISA 0
+NMI ... going to debugger

Can anyone suggest how I could diagnose these errors? I saw some
suggestions that memory faults might be a cause of similar problems but
Memtest came up clear.

Please cc me because I'm not a subscriber.

Thanks in advance,

Peter Risdon