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I have a HP desktop machine with Ubuntu 14.04, with also Xubuntu and Gnome desktops installed. I mostly use the Xubuntu session.

When using the Xubuntu session, when I power off my monitor, and power it back on, the screen stays black and I cannot do any work. With ctrl-alt-f6 I can open another virtual terminal, and then the screen works again, but if I to go back to the desktop session with ctrl-alt-f7, all I have is a black screen.

But, if I login to Unity (the Ubuntu default session), or to Gnome, and turn the monitor off and back on, everything works ok. Also, if I log out, and while in the lightdm greeter, turn the monitor off and back on, everything works ok.

What could be the cause for this, and how to fix this?

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I cannot reproduce this issue, but I wonder if this is related to a similar bug when going into standby ? There is a fix at bugs.launchpad.net/ubuntu/+source/xfce4-power-manager/+bug/… if that does not work, I suggest filing a new bug report. –  NGRhodes Jun 5 at 9:46
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1 Answer 1

I had this same problem with a brand new installation on my old Thinkpad T43. I made some changes in the settings that not only fixed it for me, but made it better than ever.

By better than ever... when I close the lid now, the computer goes into full suspend mode (not just blanking the screen). When I open the lid, it immediately comes back, with no login prompt, ready to use. This may not be what you want, but it might be what fixed the blank screen problem - I really haven't investigated because I kind of like it this way.

Now, unfortunately, I made a few changes at once, so I'm not sure exactly which one is important, so I'll list some settings that I have made.

Power Manager Settings

  • General - checkbox for "Monitor power management control" is checked.
  • On AC (and on Battery) - When lid is closed, Suspend. Put computer to sleep... Never

Light Locker Settings

  • Locking - "Enable Light Locker", Off
  • Lock on Suspend, Off (but disabled, so probably doesn't matter)

In case I missed something, if you have any questions, feel free to ask

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