Comment 52 for bug 49521

I've just now, with 14.04 (fully updated as of the date of this message) had a similar problem on my Lenovo T510. However, it seems somewhat variable with the standard (open source) Nvidia driver. (I've set my logind.conf to ignore lid close rather than suspend, but I saw similar issues before I did that.)

Most of the time, on closing the lid and re-opening it, I'm greeted with a black display, and Ctrl-Alt-F1 will not bring up the console window. However, Ctrl-Alt-Del will still reboot the machine. On two occasions, however, the display came back normally after re-opening the lid, and on one occasion the machine locked up so badly that Ctrl-Alt-Del wouldn't reboot nor would even the caps lock light come on when pressing the caps lock key.

Switching to the closed source Nvidia driver seems to have fixed the problem for me.