As of a couple days ago, the button and keyboard command for Subscript don't
do anything. I tried removing and replacing the button, doing so with a
reboot in between, changing the keyboard shortcut, repairing Word from the
program and from the install CD, removing and reinstalling the program, all
with no help.

Is there a way to create a -new- toolbar button with the subscript function?
Or is there a registry key that's holding some weird preference?