'not works in BIOS but not in Windows 7' sounds more like a typo to me.
If its not working with your pc, try to attach it at some other pc to see whether it is working or not, or you can even try other keyboards in that ps/2 module.
If the problem continues then go to service center with your mobo.
There is no problem with the motherboard. The keyboard is OK as it works properly in
BIOS as well as
Windows 7 32 bit, on the same motherboard. The problem is with
Windows 7 64 bit.
Also the NUMLOCK, SCROLLOCK, CAPSLOCK and OFFICELOCK buttons, when pressed nothing happens in the OS but the LEDs in the keyboard respond. This proves that the keyboard and the mobo are OK and the problem is with OS.
Visit these links and please tell if one of these could help me:
PS/2 keyboard works in BIOS but not Windows?
Windows 7 keyboard problem - Microsoft Answers