To change hostname in Ubuntu or any Debian variant Linux, modify the /etc/hostname and /etc/hosts.
sudo vi /etc/hostname
Change the old hostname to a new hostname.
sudo vi /etc/hosts
Also, change the oldhostname to a new hostname,
After done, changing the /etc/hostname and /etc/hosts, you need to restart the hostname service.
sudo /etc/init.d/hostname.sh stop
sudo /etc/init.d/hostname.sh start
And then you log out from the shell and log in back. Once logged in, type
to check on the changes you have made for the hostname.
I use a laptop with Ubuntu 8.10 installed at work. While running the some high process, the CPU temperature get really high and its automatically shutdown the system. This thing happen every 2 or 3 days and its really annoying. The syslog showed the following error message:
ACPI: Critical trip point
Critical temperature reached (100 C), shutting down.