Well, I was using DX10 Dynamic, and was crashing about 50% of the time when trying to load saved games.
So I tried what was suggested elsewhere, switching to DX9 Enhanced Dynamic, but now on load it crashes with an error:
xrEngine.exe caused ACCESS_VIOLATION in module "E:\Games\S.T.A.L.K.E.R. Clear Sky\bin\xrEngine.exe" at 0023:0045E250, shared_motions::motion_def()+16 byte(s)

Does anyone have a solution for this??

My system:
Windows 7 64bit
Intel i7-3820 (Sandybridge E)
16GB RAM
GTX 980 GPU