fn-backspace no longer working on MacBook Leopard in WinXP Bootcamp

I installed Win Xp2 on my MacBook Leopard with success but fn-Backspace (canc) and fn-Arrows worked only for few days, now fn-Backspace is Backspace only (and so on).
I don't know what I did wrong, probably is after are been installed udgrade 5.1 and the keyboard fix (1.1).
Anyone has some idea?
thanks
Eleonora K.

I use this software: http://www.olofsson.info/index.html?inputremapper.html

You can remap the Apple keys so they work better in Windows (fn+delete = delete, Apple key = Windows key, etc.)