Wireless keyboard affecting screen

[Pyroman]

Riddle me this. Why would a wireless keyboard cause the screen to go fuzzy? I've been called to a projector with a wireless keyboard that intermittently goes fuzzy but as soon as you pick up and shake/prod/provoke the wireless keyboard then the screen returns to normal. I've not changed the batteries yet in it but just the fact it's causing a problem is blowing my mind. Thoughts?