Problem starting up X

[fkrogh2]

This is a new install of 14.04. Sometimes system boots into X just fine. Other times it stops with a screen with some dots in diagonals. Typing <cntrl> <alt> <F?> where ? is any digit but 7, followed by <cntrl> <alt> <F7> and all is well. I'm hoping there is some thing to try that will get this working properly all the time. I am using the nvidia drivers. Thanks,
Fred

[fkrogh2]

Found a fix. Inserted a line "sleep 2" just before "exec lightdm" in file /etc/init/lightdm.conf. Evidently this problem has to do with using an SSD.