Bad display resolution in xUbuntu 15.10 and failing display setting

Have you tried the Intel driver installer. OmgUbuntu has a guide

Thanks. I tried it but the problem persists. Any other hint?

What is the output of the following diagnostic commands

uname -a
lsb_release -crid
sudo lshw -C display
xrandr

Hi.

Sorry for dealy. The diagnostics are:

uname -a
Linux muminek 4.2.0-18-generic #22-Ubuntu SMP Fri Nov 6 18:25:50 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

lsb_release -crid
Distributor ID: Ubuntu
Description: Ubuntu 15.10
Release: 15.10
Codename: wily

sudo lshw -C display
  *-display
       description: VGA compatible controller
       product: Xeon E3-1200 v2/3rd Gen Core processor Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:27 memory:f7800000-f7bfffff memory:e0000000-efffffff ioport:f000(size=64)

xrandr
Screen 0: minimum 8 x 8, current 1400 x 1050, maximum 32767 x 32767
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VGA1 connected primary 1400x1050+0+0 (normal left inverted right x axis y axis) 410mm x 257mm
   1280x1024 75.02 60.02
   1440x900 74.98 60.07
   1280x960 60.00
   1152x921 76.03
   1280x800 74.93 59.81
   1152x864 75.00
   1024x768 75.08 70.07 60.00
   832x624 74.55
   800x600 72.19 75.00 60.32 56.25
   640x480 75.00 72.81 66.67 60.00
   720x400 70.08
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
  1400x1050 (0x4a) 156.000MHz
        h: width 1400 start 1504 end 1648 total 1896 skew 0 clock 82.28KHz
        v: height 1050 start 1053 end 1057 total 1099 clock 74.87Hz

Many thanks for any help.

See https://wiki.ubuntu.com/X/Config/Resolution#Setting_xrandr_changes_persistently for different possibilities to change the display resolution at every boot or login.

There is one thing that puzzles me a bit: You are stating "The correct resolution is 1440x900 at 75 Hz.", but the usual meaning of the resolution named "1440x900_60.00" would be 1440x900 at 60 Hz.

You might use the command
cvt 1440 900 75
for the modeline details of 1440x900 at 75 Hz.

Thanks for your previous answers. Nonetheless, could you possibly clarify some points? (I'm not well versed in this stuff.)

I'm using xUbuntu 15.10 with xfce4. So there is neither gdm nor kdm (in fact, I don't know what I use instead; perhaps lightdm but I can't find its .conf file). I cannot find xorg.conf nowhere in system too (neither in /etc, nor /usr).

So the only way I can use is using .xprofile. However, when I put there
     xrandr -s 1440x900
I get the following error message when I log in:
    Error found when loading /home/XXX/.xprofile:\n\nSize 1440x900 not found
    in available modes\n\nAs a result the session will not be configured correctly.
    You shall fix the problem as soon as possible.

When put there
     xrandr --output VGA1 --mode 1440x900
I get the following error message when I log in:
     Error found when loading /home/XXX/.xprofile:\n\nxrandr: Output VGA1 is
     not disconnected but has no modes
     Size 1440x900 not found
     in available modes\n\nAs a result the session will not be configured correctly.
     You shall fix the problem as soon as possible.

However, in both cases the resolution is set up correctly and I can even run Display setting.

I should also mention that my hardware worked well with xUbuntu 15.04 and older and the problem appeared only when I upgraded to xUbuntu 15.10.

Can you help me to configure it properly?

Many thanks.
Michal

Apology. I found that it doesn't set the resolution.

When I run "xrandr -s 1440x900" from terminal, it works. When I put it into .xprofile, it throws an error message but doesn't set the resolution. (However, yesterday it worked when I rebooted. I'm puzzled.)

Best wishes,
Michal

If you use startup manager from the dash it should run