Hey all, I need help with a particular bug. This manifested suddenly in my installation, without any tweaks or new mods:

http://imageshack.us/photo/my-images/20/9ms.png/

Apparently, the shader fails to apply lighting to foliage, resulting in this rather jarring look. I'm at my wits' end. My computer meets all the necessary requirements, I don't have any texture overrides installed, and none of the mods affect the environment. It's rather annoying.