DOH! I was using "4" as my heal-the-tank button (ctrl=renew, alt=PW:shield, normal=lesser heal) and was sure that the ctrl+4 keybind was onbound. It turned out that I had unbound ctrl+2 ...
Now I just need to setup a sheep macro, then Ragefire Chasm will be punished!


Btw - thanks for all the answers - makes me believe that I can actually get this thing going :-)