[GTALUG] server questions - - help needed

[o1bigtenor]

Greetings

I am quite new at running a server so hopefully the question isn't too
out there.

My server has been operational for about a year and I am working on a
number of different projects on it. Twice now (this last friday and 5
weeks early I came into the office to find that the server has somehow
been taken down and  has rebooted itself (process setup in the bios)
but as it doesn't quite complete the boot process, I have to hit a key
to tell it to continue and then finally to log in to read Debian
(stable).

So I am trying to determine what may have caused the system to do a
reboot, whilst I have my suspicions I want to figure out exactly what
is happening to cause this kind of behavior. AIUI servers should be
able to run happily for years without issues (barring hardware
problems) so I want that kind of reliability. Where in /var/log will I
be finding the most clues as to the events that lead up to this
'reboot'?

Thanks in advance!!

Dee