I cannot now see the session login screen - just a blank black screen. No icons, no username box etc. is displaying.
This is on a Compaq Presario c700 laptop running Ubuntu 13.04. Yesterday the machine was running fine and it was shut down normally. No changes have recently been made.
Today I switched on and the OS seemed to be booting up OK, accepted my password for the encrypted volume and the progress screen progressed to the point where I expected the desktop session login screen to show - but nothing!
Gnome, Unity and LXDE desktops are installed with LXDE being the current session.
Any suggestions appreciated.