Ubuntu 12.04 - gnome-settings-daemon crash and problem with fn keys

Question

I know there are many questions similar to this, I've been reading them and searching for a solution for 2 days but no luck so far.

I have a Samsung NP550P5C laptop and just installed Ubuntu 12.04.3 on it. When I first installed there was nothing wrong, all the function keys, like brightness and volume adjustment, were working perfectly fine. Then I ran the updates including the kernel update. And suddenly my Fn keys stopped working, even before I rebooted. I spent a couple of hours trying to solve it but it didn't work. So I did a fresh install again. I read somewhere that it could be the kernel update that causing it, so this time I didn't do the kernel update. It was ok this time until I rebooted after the updates, but after the reboot they again stopped working. Only the touch pad enable/disable and screenshot keys are working now.

I tried installing samsung-tools, samsung-laptop, nothing changed. Also when I go in to System Settings->Keyboard->Shortcuts and edit a shortcut, actually it recognizes the key, for example when I hit Fn + F8 it shows as "Audio raise volume".

Plus, when this problem with the function keys occurs, there's always a slight change in the graphics, like in firefox and vlc player the buttons are more edgy than before. It looks like something messed with the themes or something.

Thanks in advance

edit: When I run gnome-settings-daemon it returns the output below and crashes.

=== xinerama setup Configuration ===
  Clone: false
  Output: Laptop attached to LVDS-0
     status: on
     width: 1600
     height: 900
     rate: 60
     primary: true
     position: 0 0
  Output: (null) attached to VGA-0
     status: off
     width: -1
     height: -1
     rate: -1
     primary: false
     position: -1 -1
  Output: (null) attached to HDMI-0
     status: off
     width: -1
     height: -1
     rate: -1
     primary: false
     position: -1 -1
  Output: (null) attached to DisplayPort-0
     status: off
     width: -1
     height: -1
     rate: -1
     primary: false
     position: -1 -1
=== Applying Configuration Configuration ===
  Clone: false
  Output: Laptop attached to LVDS-0
     status: on
     width: 1600
     height: 900
     rate: 60
     primary: true
     position: 0 0
  Output: (null) attached to VGA-0
     status: off
     width: -1
     height: -1
     rate: -1
     primary: false
     position: -1 -1
  Output: (null) attached to HDMI-0
     status: off
     width: -1
     height: -1
     rate: -1
     primary: false
     position: -1 -1
  Output: (null) attached to DisplayPort-0
     status: off
     width: -1
     height: -1
     rate: -1
     primary: false
     position: -1 -1

(gnome-settings-daemon:2955): Gdk-WARNING **: The program 'gnome-settings-daemon' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadMatch (invalid parameter attributes)'.
  (Details: serial 274 error_code 8 request_code 140 minor_code 30)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the GDK_SYNCHRONIZE environment
   variable to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Additional commands and outputs:

sudo uname -u

Linux yunus-550P5C-550P7C 3.8.0-31-generic #46~precise1-Ubuntu SMP Wed Sep 11 18:21:16 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

sudo lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04.3 LTS
Release:        12.04
Codename:       precise

sudo dpkg -l | grep xserver-xorg-video-intel

ii xserver-xorg-video-intel-lts-raring 2:2.21.6-0ubuntu4.1~precise1 X.Org X server -- Intel i8xx, i9xx display driver

cat /etc/X11/default-display-manager

/usr/sbin/lightdm

sudo apt-get install lightdm

Reading package lists... Done
Building dependency tree       
Reading state information... Done
lightdm is already the newest version.
The following packages were automatically installed and are no longer required:
  xbindkeys thunderbird-globalmenu
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

Answer 1

1st Method

Try to reconfigure lightdm (if it doesn't solve your issue then go for 2nd Method)

• Open terminal(CTRL+ALT+T) and execute following command:

  sudo dpkg-reconfigure lightdm
  

• Then chose lightdm from the list.

_{(source: akamaihd.net)}

• Restart your system:

  sudo reboot now
  

It may fix your issue. If doesn't fix then follow 2nd Method.

2nd Method

Installing a new display manager can fix your problem. Steps to install GDM(a display manager much like lightdm):

• Open terminal(CTRL+ALT+T) and execute following commands:

  sudo apt-get install gdm
  sudo dpkg-reconfigure lightdm
  

  then chose gdm from the list:

_{(source: akamaihd.net)}

    sudo reboot now

• If it's still not fixed, try removing lightdm after installing gdm:

  sudo apt-get remove --purge lightdm
  sudo reboot
  

Hope these methods solve your issue. Reply for further assistance.