Comment 12 for bug 963633

unity --reset and logging back in seems to have fixed it for me as well, though the process did "scary" things to the desktop and on the terminal where I ran it which adds a bit more newbie unfriendlyness to the whole issue.

Having said that, I don't think 3d ever worked on this machine before and the user feedback in 3d is *much* better than in 2d, so that's a great improvement, even with this issue.