Yes I have discovered that VBA Code Obsfucation is not an exact science.
In the project I was obfuscating I had an onLoad event. Which I don't actually do anything with but always include if I want to do so in the future.
So I deleted it and you guessed it I no longer get the two 400 Errors. So most probably as you suggested the Ribbon was still executing the callback. The reason there were two was I have two instances of the project to obsfucate open. The initial a Read Only which I then do a SaveAs for the obsfucated version.
On an even happier note the Conway's Game of Life project obsfucated successfully on my latest VBA Code Obsfucator version and all the code worked perfectly.