It may not have damaged your computer, but you shouldn't use the Mac download on a Windows, because I think there would be subtle changes in the folder that can mess your whole game up. xD
Well I didn't use the Mac download, I just compared the files. I had it on my Mac at one point aha
Here's a quick question: Did your copy have grass.object in the object folder? Because mine didn't uhh
Oh and I tried installing mass markings. It didn't change anything.. So it's not in the config or images. At least, I'm pretty sure it isn't...