Meshing problems

I suffer a lot of problems with meshing geometries. Geometries are imported from IGES or STEP. They are not very complicated. I performed a lot of checks on geometry with a variety of tools which all indicate that there are no problems here. Also Salome in geometry indicates no errors and rendering looks perfect. However meshing in Salome using Netgen1D-2D-3D gives errors like: OCC exception, COMP_ERR_EXCEPTION. This both occurs when geometry was imported as IGS and STP.
Can anyone explain what this means and how to solve this frustrating error? Note that I have tried tens of variations in geometry building, accuracy settings etc and I am convinced that the problem is no longer in the geometry.
Hope someone can help me a bit further.

Mark