14.04, locked screen to go to lunch, upon return from lunch cat was sitting on keyboard, login screen was frozen & unresponsive.
To replicate: In unity hit ctrl-alt-l, place keyboard on chair. Sit on keyboard.
Resolution: Switched to virtual terminal, restarted lightdm, lost all open windows in X session.
What should have happened: lightdm not becoming unresponsive.
Found the story behind this bug neat, that is why I wanted to share it.
Something similar to this.
I remember reading about a kid who bypassed the Xbox parental control just by inputting 0000. It was a bug in the software.
I can’t find the source for this but I remember this.