Totally black above the horizon except for trees, radio towers or buildings that extend above it. No stars at night, no clouds no sun on the horizon at dusk or dawn. The simulator is fluid now compared to before, stutters are for the most part gone. That was my main problem before. edit:Need to add that in windowed mode the top 1" or so of the screen doesn't refresh. What ever is up there, stays there.Any ideas?

Wasn't there a tweak from Phil's blog about dusk/dawn smoothing, the integer points at which each occur? Did you add these to your FSX.cfg file by chance with wrong numbers? You might try renaming your fsx.cfg file to fsx.cfg.old and build a new one and see if the same problem persists. Also, make sure non of the default scenery directories are unchecked in the Scenery Library.That's all I can think of at the moment...

I renamed the FSX.cfg so it would rebuild and now have clouds but still have a black sky. No dawn sun although it does refelect off the plane and buildings. I hadn't changed anything in there anyway

Isn't there a dawn/dusk smoothing checkbox in the FSX display settings? Is that checked?

That sounds familliar but I can't find it anywhere.