I'm reporting this issue as this caused a moderate amount of stress on my part to figure out why I could not launch P3d v4, when I had no previous issues.
My symptoms were that I would click on p3d, the splash screen would display for a few seconds, then disappear, and the p3d scenario startup screen would not display, making p3d unusable.
I was able to determine that p3d was running in the background by checking the task manager. I would force quit the process, restart, try launching p3d again, and the same thing would happen.
I posted a thread to the Lockheed forum which was replied to by one of their support people to try the usual troubleshooting steps. Nothing worked. I was getting really stressed.
Looking around on the p3d forum, I noticed other users having the same problems. Lockheed was saying this may be caused by USB devices, or a corrupt entry in the created documents folders (appdata/roaming, programdata, appdata/local). Nothing Lockheed suggested worked.
Another user posted a comment in my thread to check the registry for a key at this location:
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers\
This key had a value of - $ IgnoreFreelibrary<bglmanx.dll
I deleted the key and P3d started up as normal.
I'm told there is a value in this key if the dll crashes. All I know, before this problem started, everything was fine. I own a lot of the FSDT and Flightbeam airports + GSX. Nothing was out of the ordinary on my last flight before the problem started. Next time I tried to launch p3d, I wasn't able to.
Hopefully this helps track down a potential issue in your systems.