machine rebooting.

[fishnyc22]

I have noticed that my machine has been rebooting itself here and there on its own. Any idea why taht would happen. is it a plesk thing or a hardware thing. How can I determine whats causing it.

the first thing in /var/log/messages at the point of reboot is:

Oct 19 17:16:46 u23423454 syslogd 1.4.1: restart.

Thanks

Fish