problem with fn keys always staying on in xp

[claremont]

I have a macbook pro running bootcamp, among other severe recent issues, I am having a problem with the fn keys on the laptop keyboard. The uio/jkl keys are stuck in fn mode, even though i am not pressing the button. When i press fn and the u key at the same time, i still get the number 4. I am typing this from an external usb keyboard which is working fine, anyone know what the problem is?

thanks a lot