I want to format a hard disk and boot from a CD, but at the point where it says "press any key" or something, the keyboard stops functioning so the computer just reboots normally. Why does the keyboard stop working just then and works at all other times?
Have you reset you're BIOS to boot from the CD first, check this first. If it is set to boot from the CD, then make sure you do have a bootable CD, (ie XP disk), or burn a bootable ISO disk.
If I could remember all I have forgotten, I would be a smart man.