[PyMOL] Stereo flipping in coot and pymol

Dear all,
our users complain that during there graphics session front and back are 
switched.
We are on Linux using NVIDA Quadro boards with 3-pin DIN connectors.
So it seems that you see sidechains behind a sheet, that are in realety 
front of a sheet.
If they were behind it, you should not see them at all.
-- 
Joachim