I am getting this error with a number of my AI projects. These are slightly older projects that I have not opened for a while. I have about three or four that I open regular and those work fine. I think that they are all based on the same original custom template but I am not sure why I am getting this error for a few of the older ones.
I have looked for "odd" text in the aip file but have not seen anything that appears out of place.