I too am having problems with just JFK
It's not possible the problem is JFK, since all products now use the same installer, which downloads just the SAME bglmanx.dll from the net, as soon as it starts. Please, verify this happens.
And, check that your firewall is granting online access to the installer, otherwise it wouldn't be able to download the most updated files.
I installed the app and then started FS X. Error message. I uninstalled and then rebooted. I then checked the scenery.cfg, dll.xml and fsx.cfg files to make sure all was back to normal.
As I've said, many times, uninstalling IT'S NOT the way to solve the issue! This error message is *temporary*, FSX sometimes BELIEVES a module has problem, but just the first time it launches it. If you simply ignore the error, ALLOW the module to run and try again, possibly after a reboot, it usually works on subsequent launches.
Running ESET for my firewall and virus protection.
If you still are having the issue, even after a reboot, and if you are sure the installer WAS able to downloads the current files from the internet when it started, try to exclude the FSX main folder from scanning in your A/V config, and try again.
Also, you might try INSTALLING with the A/V off because, if the A/V mistakenly identified the dll as a virus, it might have blocked the *udpate*, so you are still running the old version, or perhaps a mix-match of versions, which might create a crash.
Just for your info, the current version of the bglmanx.dll file, that you can check by right clicking to it and selecting "Properties->Details", is 2.5.1.2