Landing light beam problem

After discovering that REX seems to have messed up the spotlight.bmp file (landing light beams were displaced), I recovered the original version of that file.Now I have the correct location of the light beams, but the beams themselves when lighting the ground don't have smooth gradients but are "stepped" like if I had anisotropic filtering disabled!My problem seems to be restricted to the landing light beams (and maybe taxi lights as well) since the sky colors look like they have much smoother gradients.I've attached pictures of both the sky with smoother gradients (though the color transitions don't look "perfect"):the landing light beam where red arrows indicate some step positions:and a screenshot of my Nvidia inspector settings:Needless to say that I let FSX create a new fsx.ini, settings for the graphics adapter (GS250) is set to 32 bits in FSX, and I already played with various driver and Nvidia inspector settings as well as graphics settings in FSX. And, I've already have REX install different landing light replacements.But maybe I've a general problem and it's more visible at night (landing light beams) and not so during the day (sky). I must say that I have a much different result if I disable anisotropic filtering: In this case, there are quite remarkable "steps" between the colors even in the sky.Do I get what's possible with my graphics adapter or do I miss something fundamental that would render color gradients even smoother?My current setup is AA off in FSX (I let the driver do that) and AF set to "anisotropic".That's driving me nuts somehow!