I have MSFS uninstalled as I wait for the update dust to settle so I can do a totally fresh MSFS install. In the meantime my FSX SE began sticking on the splash screen. I went through a number of FSX SE gyrations, uninstalling, reinstalling, repairing, etc. without success. I kept searching the internet daily for clues. Finally I found a new post on the SteamCommunity.com site that resolved my issue. Turns out in my case it was a file placed by my recent nVidia driver update to 471.11. The file was in the primary Windows folder. Filename was "NvCamera32.dll". It was not appearing in the list of files in that folder in my file manager. I did a search for it in that folder and the search did find it. From the search results I was able to delete it. That solved my starting issue and I am back up in the air. Because I found success in deleting the file I am uncertain if a driver rollback would have done the same. Here is the link to the discussion:
https://steamcommunity.com/app/314160/discussions/0/3046104862447471029/