Ubuntu 8.04 won't Shutdown, but it will reboot

[youghta]

I have a new Ubuntu 8.04 installation, and I have noticed that I cannot shut the machine down. I'm running it headless, and when I attempt to shut it down (shutdown now), it never powers off, and the machine remains pingable, but I cannot ssh into it. Rebooting the box works like it should. I know that I haven't included enough information, but I was hoping that somebody could point me in the right direction to begin troubleshooting this.

I followed all of the instructions that are posted for Ubuntu 8.04 installation.

Thanks in advance!

[pilotbabo]

Try using poweroff command. It is working here.