Are you saying that you don't have the problem on an airport that doesn't have AES ? There's simply no reasons for this, and nobody reported it before.
In any case, you never have to "reinstall" GSX, it's possible that FSX didn't closed properly because of other addons installed, check if you have a Couatl.exe process running on the Task Manager before you launch FSX, and if you have, terminate it manually, then launch FSX.
