It is as simple as that: Your Action Design plugin, or whichever is his name, supposes to work only with Mozilla, or at least an alert(in IE) tells us so. Why? How should we know? It is probably a Mozilla's add on, or something like that.
o3d works in both browsers, I added the alert myself until I get it working in IE. I managed to get the sidebar to appear in IE when I asked the community a few months back but I want to try and get the hole thing working in IE now