When I try to install Ubuntu 12.04 AND 12.10 on my old computer, the keyboard and mouse stop working. I know that they are working because when I am in BIOS, the keyboard works.

I already try to do everything:
• Installed a external keyboard (this keyboards is working on the BIOS too)
• Try to use another copy of Ubuntu 12.04 AND 12.10
• Reconnect the keyboard cable.
• Try to install Ubuntu with a bootable pen-drive

But the problem persists. What can I do?