If you added a vid card, and updated drivers, THEN you had FSX issues....I would suspect that automatically. Search for older drivers and see if you can upload those successfully.
I saw the "brand new video card" statement, but, that may not explain it.
If you flew on FSX for a couple weeks with this new video card, it may just be the newest drivers automatically loaded and screwed you up.
If it was the first time since you hooked up the video card and such, then it bombed on you, the see if there are older drivers for it (yeah, I saw your post saying you would look for older drivers and I know you aren't dumb. You have been here a long time dude).
Only reason I post is because I have a laptop that has been reliable for years until last month. It wasn't even a Nvidia driver that got my laptop screwed up, but, apparently a windows driver. I am using win7 home prem 64 bit, and I can't figure out what is going on with the video driver. It crashes on startup, not upon loading a program like fsx, so you are ahead of where I am at. As long as I do a fresh Win7 64 install and don't let it update the video driver, I am okay. I have done this 4 times before learning I am screwed. Good luck Mal!