0

I'm running 64-bit ubuntu 14.04. I'm experiencing a problem that started just a few days ago: every now and then, on reboot, my screen resolution is too narrow, with black unused screen space to the left and right. The pointer tends to flicker when this happens. I'm able to fix it by rebooting, which works more or less randomly (it might take several reboots).

When the problem occurs, the resolutions listed under Settings > Displays are 800x600 (4:3) and 1024x768 (4:3). The correct resolution of 1366x768 (16:9) does not appear.

Strangely, the login screen is displayed correctly (i.e. full-width resolution, taking up the entire screen) -- the problem only appears after I log in.

Why does this happen? Why did it only start a few days ago, when I've had 14.04 on this laptop for years? What can I do to make it go away?

Edit: here is the output from xrandr in the good state (i.e. when there is no resolution problem):

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 32767 x 32767
LVDS1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 293mm x 164mm
   1366x768       60.0*+
   1360x768       59.8     60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
VGA-1-2 connected
   1024x768       60.0  
   800x600        60.3     56.2  
   848x480        60.0  
   640x480        59.9  
  1024x768 (0x43)   65.0MHz
        h: width  1024 start 1048 end 1184 total 1344 skew    0 clock   48.4KHz
        v: height  768 start  771 end  777 total  806           clock   60.0Hz
  800x600 (0x44)   40.0MHz
        h: width   800 start  840 end  968 total 1056 skew    0 clock   37.9KHz
        v: height  600 start  601 end  605 total  628           clock   60.3Hz
  800x600 (0x45)   36.0MHz
        h: width   800 start  824 end  896 total 1024 skew    0 clock   35.2KHz
        v: height  600 start  601 end  603 total  625           clock   56.2Hz

Edit: I just rebooted into the bad state (narrow screen with black on each edge). Here's xrandr:

Screen 0: minimum 320 x 200, current 1024 x 768, maximum 32767 x 32767
LVDS1 connected primary 1024x768+0+0 (normal left inverted right x axis y axis) 293mm x 164mm
   1366x768       60.0 +
   1360x768       59.8     60.0  
   1024x768       60.0* 
   800x600        60.3     56.2  
   640x480        59.9  
VGA2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
VGA-1-1 connected 1024x768+0+0 0mm x 0mm
   1024x768       60.0* 
   800x600        60.3     56.2  
   848x480        60.0  
   640x480        59.9  
  1024x768 (0x43)   65.0MHz
        h: width  1024 start 1048 end 1184 total 1344 skew    0 clock   48.4KHz
        v: height  768 start  771 end  777 total  806           clock   60.0Hz
  800x600 (0x44)   40.0MHz
        h: width   800 start  840 end  968 total 1056 skew    0 clock   37.9KHz
        v: height  600 start  601 end  605 total  628           clock   60.3Hz
  800x600 (0x45)   36.0MHz
        h: width   800 start  824 end  896 total 1024 skew    0 clock   35.2KHz
        v: height  600 start  601 end  603 total  625           clock   56.2Hz

Edit: rebooted again and I'm back in the good state, no idea why...

Edit: the fix in the answer below worked for a while, but the issue occurred again today (for the first time in several weeks). I think it's related to accidentally hitting windowskey+P -- see How to stop Mod4-P from switching the display?.

Here's a screenshot showing the second, "bad" display:

displays

Improve this question

1 Answer 1

Reset to default
1

I don't know why it would switch but as a temporary solution does doing xrandr to force it to the specified mode you want work?

xrandr --output LVDS1 --mode 1366x768

You can also check this article for more useful information: https://wiki.ubuntu.com/X/Config/Resolution#Setting_xrandr_changes_persistently

Improve this answer
5
  • Thank you for posting this. It almost works, but not quite. I'll post a screenshot.
    – Adrian
    Mar 29, 2016 at 7:09
  • After running this command my desktop is tiled, with the date on the bar at the top of the screen appearing twice. It almost looks like I have a low-resolution desktop being displayed on top of a higher resolution desktop. When I go to Settings > Displays I see two displays listed: "built-in display" and "unknown display." If I switch off unknown display (after running the xrandr command you suggested), everything looks good.
    – Adrian
    Mar 29, 2016 at 7:15
  • Yeah I'm not sure why in the first example you have where everything is good the VGA option is shown as "VGA-1-2 connected" but in the second it says "VGA-1-1 connected." It even shows a star in the second output like it's trying to use that display. Do you only have the normal laptop display or do you have another, VGA, display hooked up?
    – AgathosAnthropos
    Mar 29, 2016 at 10:29
  • I only have the laptop display -- nothing plugged in by VGA. The issue I described in my post just happened again today -- I think it's related to accidentally hitting windowskey+P.
    – Adrian
    Apr 14, 2016 at 15:52
  • See askubuntu.com/questions/20113/…
    – Adrian
    Apr 14, 2016 at 15:53

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .