My keyboard is Working with BIOS.
Whenever I install my system it boots properly, but the keyboard is not functioning.
Why is this problem occurring?
If you're using a USB keyboard, then Windows XP may need some time to detect it and determine which driver to use (up to 10 minutes on slow machine -- go have a coffee or play an MMORPG or answer other questions here in SuperUser.com {the very best option} while you wait).
If you're not up to Service Pack 3 yet, then you may need to revert to a PS/2 keyboard and get Windows XP updated to Service Pack 3 before it can detect your PS/2 keyboard.