Comment 70 for bug 459639

"The triggering factors of this bug can range from hardware to installed packages to how fragmented your drive is and how much drive seeking for components happens during load. None of these are really the cause. The cause is that upstart optimized for fast start up is starting X before the underlying system is ready in some systems and under some circumstances."

Which means best-case scenario we need to look at reconfiguring upstart.

I was reading https://wiki.ubuntu.com/MeetingLogs/devweek1007/UpstartJobs and came across a good suggestion:

this command:
sudo initctl log-priority info

will cause upstart to output information in /var/log/syslog. I'm going to give it a shot later with & without "sleep 2" and see if I can get any interesting output.

That chatlog also has a few other insights into what may need to be done to get to the bottom of this.