All fsdt airports I have install are purchased and verified with my serial numbers, so that is not the case. So, you are right, I'm referring to the cache regeneration message from GSX. I have added some new sceneries, such as FTX regions, but even before adding these new addon, I was still getting that GSX message. I'm one of the few, I guess, that has not made the leap over to P3D, so I'm sure it has nothing to do with the switching between the sims. Perhaps I should download the stand alone addon manager and see if that helps any?