I have had this same problem before. The problem is with one of your planes panels. I have discovered that FS9 will do this if the panel of a airplane is not correct or trying to load a gauge that is not there. About all you can do is to check all of your planes panel folders to see if you can spot a problem.If you do not see anything wrong then move all but one of your air craft to a different folder and restart fs9 then keep adding one plane at a time untill you get the message again than you know that it was the last plane you added that has the problem. Make sure you check all of your planes do not stop on the first one you find as there may be others.This is what i did and i discovered that a plane panel was being alaised to a plane that no longer existed. 8)