It happens to me too: if I go out of the workstation for a while - and the screen saver activates, which is also a blank black screen -, when I get back and touch the mouse sometimes the screen shows up as if no screen saver has been activated, that is, it shows what was shown before the screen saver activated, all the application windows, the mouse moves but the keys doesn't seem to work.
The only way around I could find was to ctrl-alt-f1, to switch to a text mode linux, and ctrl-alt-f7 to come back to the graphic mode, and then it's easy to understand what was happening: it shows the (un)lock screen with a few keys already entered in the password field. So, to me, what's happening is that, on cancelling the screen saver and putting up the (un)lock screen, which probably is an overlay of some kind, something is failing badly and the overlay doesn't show up. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/757400 Title: Lock dialog doesn't appear when screensaver is active To manage notifications about this bug go to: https://bugs.launchpad.net/unity/+bug/757400/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs