kernel crash on Intel(R) Xeon(TM) CPU 2.66GHz 4-cpus machine

[Andrea Puglisi]

Hi everyone,

I've installed ubuntu breezybadger and upgraded up to Ubuntu 6.06 LTS a 
couple of days ago, on my machine with 4 Intel Xeon cpus (2.66Ghz); just 
yesterday I've upgraded the kernel (which was originally -386) to 
2.6.15-26-686 in order to exploit the multiprocessor architecture

everything was working very well; SO well that I finally launched the 
execution of four numerical simulations (scientific work)

a couple of hours ago I was working on the machine (while the four jobs 
were running smoothly since 20 hours) when it suddenly froze up completely

screen frozen, keyboard frozen, mouse pointer frozen, alternate screens 
inaccessible, network interface frozen (no ping from remote): death of the 
system

I've never seen such a horrible freeze in many years of heavy work with 
linux&c

I rebooted (simulations to be started again, sob!!) and then browsed 
carefully all log files; I've found no message at the time of the freeze, 
nothing to be used as the smallest hint

my machine contains: 1Gb of physical ram, 2 ide hard disks (master/slave) 
with 80Gb each, an external usb disk with 150Gb (used to store the data 
from the simulation), and an energy backup apc (ups pro 650)

as I told you, the installation was done two or three days ago and the new 
686 kernel was installed just yesterday; before this freeze the system was 
up since 20 hours, perhaps more; this is why I have NO IDEA of which has 
been the critical event triggering the crash

note that this machine has been working well since three years with 
FreeBSD, I would exclude hardware problems

Please, give me any kind of idea, a test or a place/file where I can find 
a track to follow and understand what happened. I cannot stand it happens 
again, otherwise I will be forced to go back to free-BSD

Thanks everybody!

Andrea