[ILUG] Unexpected system restarts

[John Kinsella]

Hi
I'm running Ubuntu 8.04  on a new-ish DellPC.
Noticed this morning that system had restarted about 22:00 last night.
kinsella at jkcray:~ >uptime
 08:38:13 up 10:19,  5 users,  load average: 0.11, 0.15, 0.27

This has happened a couple of times in the last month.

Its possible that builders working late knocked power off on the power 
connection.

If that is not the case can anyone advise where to start when looking 
for the cause?
(System logs seem the obvious place -
kinsella at jkcray:/var/log >ls -lt|more
total 47344
-rw-r----- 1 syslog adm    24210 2008-10-01 08:40 auth.log
-rw-r----- 1 syslog adm   149106 2008-10-01 08:40 messages
-rw-r----- 1 syslog adm    13867 2008-10-01 08:40 syslog
-rw-r----- 1 syslog adm   156365 2008-10-01 08:16 kern.log
-rw-rw-r-- 1 root   utmp    1920 2008-10-01 08:15 wtmp
-rw-r----- 1 syslog adm    30594 2008-10-01 08:08 mail.info
-rw-r----- 1 syslog adm    30594 2008-10-01 08:08 mail.log
-rw-r----- 1 syslog adm    30206 2008-10-01 08:06 daemon.log
-rw-r----- 1 syslog adm      505 2008-10-01 08:05 user.log
-rw-r----- 1 syslog adm    28993 2008-10-01 08:05 debug
-rw-rw-r-- 1 root   utmp     384 2008-10-01 08:04 btmp
-rw-r----- 1 root   adm        0 2008-10-01 07:58 dpkg.log
drwxr-xr-x 2 root   root    4096 2008-10-01 07:57 apt
drwxr-xr-x 2 root   root    4096 2008-10-01 07:57 cups
-rw-r----- 1 syslog adm   221282 2008-10-01 07:40 syslog.0
-rw-r--r-- 1 root   root   66669 2008-09-30 22:20 Xorg.0.log
-rw-rw-r-- 1 root   utmp   97536 2008-09-30 22:20 wtmp.1
-rw-r----- 1 root   adm      344 2008-09-30 22:20 acpid
drwxr-xr-x 2 root   root    4096 2008-09-30 22:20 gdm
-rw-r----- 1 root   adm    32818 2008-09-30 22:20 dmesg
-rw-r--r-- 1 root   root  335587 2008-09-30 22:18 udev
-rw-rw-r-- 1 root   utmp  292876 2008-09-30 18:47 lastlog
)

(The system was not particularly heavily loaded and I didn't leave any 
number-crunching processes running.

Thanks for any advice.

John

-- 
John A. Kinsella		Ph: 	+353-61-202148 		(Direct)
					+353-61-333644 x 2148  	(Switch)
Mathematics Dept.		e-mail: John.Kinsella at ul.ie
University of Limerick		FAX: 	+353-61-334927
IRELAND				Web:    http://jkcray.maths.ul.ie