[Dudelive]

First of all you stated you did an upgrade and then this started, was this an upgrade or a clean install of the OS?
Also try using an adapter to go from usb to ps2 so it will work as a ps2 keyboard till all is installed and working....I have had sorta of the same thing happen before.
Try the keyboard on another computer.
Also try letting it find the keyboard when booting when you are using a PLAIN old style keyboard, with out the bells and whistles.
If you did a clean install of XP, go in device manager and remove the keyboard and reboot as will be stated. Xp should find New Hardware detected upon booting and should install the correct drivers.
This is based on using XP 32 bit and not 64bit as I have not used that one yet.

Good Luck and keep us posted as what was the problem.

Thanks
Dudelive