Comment 6 for bug 245888

You're absolutely right, that was the issue (at least why the screen was white). I had set that in my .bashrc which I recently deleted. Setting LIBGL_ALWAYS_INDIRECT gives a black screen and more or less freezes X (Ctrl+C doesn't kill compiz, switching to a VT and killing locks up the machine, expectedly). More details in an hour when I get out of class and find a machine to remote in from.