Howdy,
You'll need to be sure that your MIDI keyboard is plugged in and active before starting up Composer. If you haven't done that, please give it a try. If you have done that and Composer isn't recognizing the MIDI keyboard, you can try the following. With your keyboard "on" and plugged into your laptop, open Composer and go to Setup -> MIDI Devices Configuration -> Config -> Initialize. This will force Composer to re-detect your active MIDI devices.
You may also need a different driver for the keyboard or interface unit for the laptop than you use for your desktop. I have a situation like that myself, where my laptop is XP, my desktop is Windows 7, and the interface unit that I use needs a different driver on each machine.
Hopefully that will get you going. If not, do let me know. If I don't respond here (I'll be going on vacation to see family in the next couple of days, and will be gone almost two weeks) then you can send an email to
support@notation.com for help.
ttfn,
Sherry