You are 100% correct that is exactly what I saw. I had completely removed all traces of FSX and tried to reinstall it on the same drive I had it on to start with fsx would install and run with no problems at all. But as soon as you installed Acceleration that is when it stated it was no longer activated.
I remember when Acceleration came out I had no desire to buy it as it really did not give me any thing I wanted as I am not big on Missions. I had to buy FSX gold when I switched over to Windows 10 64 bit the standard version I had would not install. Of course I have heard that is no longer the case.
My solution to the problem was really simple I installed FSX I than installed service pack 1 and service pack 2 and it works like a champ.
Acceleration give you service pack 1 and service pack 2 some extra missions and extra aircraft and a few other minor things so I did not install it
I looked everywhere to find out the reason as to why Acceleration never asked me to register it and found nothing anywhere.
How in gods green earth are you supposed to activate a program that never asks to be activated?????
I had even found a registry cleaner from Microsoft that did seem to remove some stray entries from FSX. But to no avail the problem was still there. FSX would work as long as you did not install Acceleration.