Comment 48 for bug 969489

Bug 1080082 has been marked as a duplicate of this one, although I'm not sure it is (I use fglrx).

Anyway, my workaround for 1.5 months with no issues and no need for arbitrary sleep has been to modify /etc/init/lightdm.conf and adding "respawn" like this:

...
stop on runlevel [016]

respawn # <-- add this line

emits login-session-start
emits desktop-session-start
emits desktop-shutdown
...

If lightdm comes up the first time, it stays. Otherwise, I see a flicker of the first one dying, and then it immediately starts up again and all works good.