Key launches Calendar and iTunes - Help!

I set up a macro to open Calendar when I press a “device key” on my external keyboard. This device key is labeled both F9 and play/pause. The keyboard is a Microsoft Sculpt keyboard, which connects to my MacBook Pro via a dongle plugged into a USB port.

When I press my device key, Calendar launches, and so does iTunes. I don’t want iTunes to launch when I press that key - ever. I have searched through all of the iTunes menus and system menus, and can’t figure out why this is happening or how to stop it. Any ideas?

USB Device Key trigger do not “swallow” the keystroke, so the keystroke is still processed by the system.

Presumably it is the system launching iTunes (probably because it wants you to choose what to Play with the Play/Pause button).