So I was playing around with the area select/fill tool in creative mode. Then after a few mistakes creating large blocks of thee wrong thing, I used the raise/lower tool to lower the terrain. And then after that, every time I look at the area I edited, the whole screen goes black. Not even the terrain around it will render. The world is completely unusable now because turning to look at that area will make everything go black.
I don't know if this is something the log catches, but.... here it is.