Optifine has a wonderful extra option in its menu, Better Snow, this allows natural ground snow to appear under things like fences, however i noticed that a texture from IC2 conflicts with this, what now appears under the fences and such is the window side of a compressor. im guessing that this is some sort of simple texture ID problem, but i thought id mention it
note: yes i did look at 1.9 IC2, the changes listed on the wiki did not mention this