I'm not sure how to describe them, but strange walls appear that completely block my view. They first appeared in a previous snapshot, around a month ago? They only happened intermittently until recently, where they have now made it impossible to play. I have restarted Minecraft and my computer multiple times, with no success.

What I've found is that some appear on chunk boundaries, while others seem to appear relative to my camera (and block my entire screen). Some were even attached to my crosshair. Not all stationary walls are aligned with an axis, some are diagonal as well. When I connected to my friend's server, I could see them, but he could not. I loaded an old world in newer and newer snapshots, and the walls appeared in 15w39c (didn't try 39a or 39b)

Probably related: A large amount of chunks don't render, though they sometimes switch between visible/invisible when placing/breaking a block.

Since it happens every time, I cannot put steps to reproduce