Does any one know how to get a USB Midi Keyboard to work in XP on a laptop?

I've just upgraded to BIAB 2011 and I've installed it on a Compaq laptop for the obvious portability, but the laptop won't let me use my keyboard. I get the usual Windows noises when I plug it in, but BIAB says "no midi input".

The keyboard works perfectly with BIAB on my old iMac and my old desktop Windows XP machines, but I can't take them with me.

Thanks

Intestinal