Problem: Macroworks suddenly and inexplicably starts coming up with the "Unit ID Conflict" error / screen, claiming one or more Xkeys has a unit ID conflict that was never there before. Happens on a previously stable system.
(OK, maybe it's not exactly "Unit ID Conflict", but it's close. I didn't write it down.)
In my case, I had a bad label printer that was causing my USB hub to reboot over and over. This confuses MW and makes "see" the same Xkeys device over and over, making it think there are multiple identical devices plugged in when there is, in fact, only one.
Removing the offending printer stopped the hub reboots, which stopped the Macroworks error.