Thanks for that idea. I tried changing from screen blanking to a screen 
saver but it didn't seem to help. I then tried just restarting X with 
ctrl-alt-backspace when it had happened, with no help - I still got no 
display on virtual terminal under F1, and F2 etc had a text terminal 
until I rebooted.

As this has followed me across computers with the shared home dir, I 
think it must be something in my account - I just really can't think of 
what user settings would affect X in this way...

James Pulver
CLASSE Computer Group
Cornell University

On 09/13/2016 10:48 AM, Howard, Chris wrote:
> Sounds like a problem with the screen saver
>
> Instead of a reboot, you could restart X with a control-alt-backspace
> I think.
>
> But I would investigate changing your screen saver, either
> turning it off or making it do something graphical and not
> just black out.
>
>
>
>
> -----Original Message-----
> From: [log in to unmask] [mailto:[log in to unmask]] On Behalf Of James M. Pulver
> Sent: Tuesday, September 13, 2016 8:42 AM
> To: [log in to unmask]
> Subject: Re: X stopping displaying on SL7.2
>
> I have now determined that it seems specific to my turning off the
> monitor. If I leave it on even overnight, X keeps working as expected.
> The problem is that the monitor is not turned off - so the backlight is
> going on a black screen all the time.
>
> James Pulver
> CLASSE Computer Group
> Cornell University
>
> On 09/12/2016 09:27 AM, James M. Pulver wrote:
>> Cross posted from serverfault:
>>
>> I'm having the weirdest issue. We use SL7.2 and have a network home
>> directory and AD + SSSD for auth. This means I can go to different
>> computers and get a consistent home dir as well as UID/GID etc. I have a
>> physical KVM to set up computers more easily.
>>
>> I started having an issue where my workstation would stop displaying X
>> to my monitor. The monitor will say "No Signal" It would work fine until
>> I switched away via the KVM to another computer, when I switched back X
>> would not display. I could connect via Bomgar and see my X session, it
>> was fine. I could ctrl-alt-F3 and the virtual terminal would display,
>> but the only way to get X back was to reboot.
>>
>> I thought it might be the KVM, so I connected the monitor via DVI
>> directly to the workstation. No change.
>>
>> I thought it was an issue with the hardware or the OS install, so I set
>> up a brand new Lenovo P510 with a new SL7.2 install. Now it will loose X
>> if I just don't use it for a while (I think it's the screen locking?).
>>
>> I thought it might be the monitor - maybe it's old and loosing signal,
>> or the new Display port to DVI adapter can be funky, so I installed a
>> brand new BENQ GW2765, connected directly via Display Port to the nVidia
>> card (this card only has Display Port connectors - 4x). No change.
>>
>> However, this last time Bomgar could not show the X session...
>>
>> So now I'm thinking - it HAS to be software, and it has to be something
>> in my configuration. But I don't really even know where to start looking
>> - /var/log/messages and /var/log/Xorg.0.log don't show anything that's
>> obvious to me.
>>
>> How can I fix X not coming back?
>>