never mind, I found it. Its the Combat flight simulator although I have never heard of it. I fly myself starting with ProPilot and ending up with MS XFS (but not under Windows 10, Win7 only). Still have TopGun and Falcon4
I'm not a CFS 2 player but I am a Flight Sim 2004 user. Microsoft put out an upgrade a while back that disabled the starting of FS9 (FS2004). I can't remember the KB number. But those that had the problem uninstalled that particular update and their games started right up again. The same might be true for CFS 2. I read about the problem on the Flightsim website. Try searching for an issue along those lines.