Put it someplace else. Seriously. If the desk is the only place you can put it, there's nothing that will keep it from skipping when you bump it because that's not the kind of vibration it's made to be isolated from. If it skips while playing without bumping the desk, make sure it's not in a location where the bass has positive reinforcement, near a speaker or where the sound from the woofer hits the desk or where the floor vibrates from the speakers. Mounting it to a wall is one way but the bracket needs to be very rigid.
