Hi, Trevor:
For what it's worth, I have used the UM-1 device (and now a UM-4) with Composer with no problems, under XP.
I've used several midi devices with Composer over the years and can't recall Composer not recognizing any device that I have installed, so I can't offer any real help, just that Composer DOES work with the UM-1.
You appear to know what you're talking about, so I assume you have re-booted since the installation of the UM-1. (That's from the "Duh!" file.)
Actually, try the device without the advanced switch on and see what happens.
Good luck.
David