I had an old desktop Compaq EVO4000 that I wanted to re-purpose as a headless server. It used to be my old Windows PC but since it was getting a little long in the tooth (and slow for most purposes) I wiped it out and installed Ubuntu 7.10 (Gutsy Gibbon) server on it. It made a great little server. The problem was it would not boot unless it had a keyboard attached. In a great stroke of irony, I received the following message during the boot up process with no keyboard:
Keyboard error. Press F1 to continue.
There is a way around this, but at first it seems a little backwards. With a keyboard attached, you have to enter the BIOS (by pressing F10 at the boot screen) and first enable a power-on password. This creates a “Password Options” selection in the BIOS menu. Then, under “Password Options,” you can now enable “Network Server Mode” which allows the computer to boot without keyboard/mouse installed. I’m posting this just in case the original place I found the answer (in the old HP forums) goes away.