Momentics assembly editor

This is probably a real simple one. I am using Momentics v2.0, build
200301241006 on an XP platform. When I am editing assembly (.s) files in
momentics, it does not allow me to cut/paste or any of the other useful edit
tools. These are all greyed out in the menu and Ctrl+C does not work. I have
changed the default editor to use the C editor (which will cut etc.) rather
than the assembly editor in preferences but I do not get correct context
highlighting. Does anyone know why this is? Is there a simple setting to get
the desired result?