No, I didn't see that rings with my setup so far.
But during my tests I saw some strange effects too. Once all rivers were showing no textures at all (only grey rectangles) while planes, buildings, airfield were displayed correctly.
I found out, that it's not only the conf.ini or not only the driver settings. It's always a combination of setting the single parameters in conf.ini and the setting of the single parameters of the driver. Only little changes might cause big problems. So a big testing effort is needed to find out a working setup without problems.
The stable setup I stated above can be loaded here (zip-file with conf.ini and shots of driver settings):
http://www.laubstein.de/temp/RangoIL2Setup.zip
The stable setup contains no anti aliasing overrides by the driver, because IL2 doesn't support additional antialising by game default. Only anisotropic filtering is set (16x).
Now I added a forced driver antialising override (8Qx, supersampling) for the next (and final) tests.
There are no rings too.
Screenshots of current test setup:
If this setup is stable too, I will post here in a few days.
Rango