trouble in booting OS doesn't get input from Keyboard

[ka_j]

My keyboard works fine initially when I have to change the bios settings, but I have to resintall the OS, when I put in the CD and try to install, it is not able to get any inputs from the keyboard, so it tries to boot from the harddrive. I have no idea whats happening, intially its working but when it tries to boot the OS it stops working. Can anyone please help me with the problem, thanks