This sounds like bugs that have occurred in at least two previous Ubuntu releases. In each case the X session was starting on the wrong console (not greater than VT6) and was being interfered with by a getty process on the same console. In each case it was very much timing related.
In the askubuntu question I cite above both people affected noted they were booting from SSD's.
When you think you are about to run into this problem, please use CTRL-ALT-F7, CTRL-ALT-F1, etc., to find out what console your X window session is active on, then go back and let it crash. After you have caught it this way please post your findings here.
This sounds like bugs that have occurred in at least two previous Ubuntu releases. In each case the X session was starting on the wrong console (not greater than VT6) and was being interfered with by a getty process on the same console. In each case it was very much timing related.
In the askubuntu question I cite above both people affected noted they were booting from SSD's.
When you think you are about to run into this problem, please use CTRL-ALT-F7, CTRL-ALT-F1, etc., to find out what console your X window session is active on, then go back and let it crash. After you have caught it this way please post your findings here.