I wanted to switch over to Unity 2D because it uses less memory, however the exit, minimise, and maximise buttons aren't showing, with just a black bar. Also the running programs do not appear in the launcher - when they are launched they appear, flash for a bit, then disappear again. Programs pinned to the launcher, like Google Chrome, flash for a bit then return to normal, with no arrow indicating the program is running.
I found the answer. Use the command
metacity --replace
. I am surprised that I didn't recieve a response to such a simple question! Well, at least I earned the tumbleweed badge :)