I dont use the wake up key on my keyboard, so i wanted to reassign it to another function since i have no application keys on it.
It seems that the computer is not even sensitive to the scancode (the message from the keyboard to the computer "E063") and that is why it does not work (i have tried reassignment in the registry). There is a partial possibility it is the OS as i use XP also. 63 is four higher than 5E and 5F (the codes for power and sleep) so Wake is probably an afterthought, and older software/computers do not support the scancode. If the computer does not respond to the wake key when asleep then the problem is in the BIOS or in the hardware (because the OS is not alert at this time). Usually the computer responds to any keypress to wake up however.
the only suggestion that may be worthwhile is to check that USB keyboard support is off in the bios (off so the OS has to handle it), other than that i have no idea. i write for future people, i know its an old post.
CB.