Re-downloading things doesn't seem to help. Even with the patch that just came out before Christmas, it's still doing this for people. I messed around with the files and stuff. If I take out, or rename the african_grass file, everything shows up white, instead of with that terrain, or any other. Similarly, if i rename another terrain from lets say.. "brownishstone" and change it to "african_grass", then every inch of terrain would be covered in the brownish stone texture. So it's probably not something wrong with the texture files, if that's even possible.
I'm thinking maybe it's a problem with terrain masks and the new patch. Either that, or maybe something with the game and the Direct3D9 rendering system, because like I said before, if I changed the rendering system to OpenGL, then the terrains will be back to normal, but then it'll crash frequently. And the drivers are all up to date on my computer.
So I don't think there's been many fixes yet.