Changing monitor on PC causes login failure.

Problem would seem to be in xorg.conf

If you can ssh in or get access to terminal you can either

A. Make manual adjustments to file
B. Reconfigure

[see] http://ubuntuforums.org/showthread.php?t=83973 Specifically the Section "Monitor" for manual adjustments

or if you want to have it reconfigured you can just run

sudo dpkg-reconfigure -p high xserver-xorg

If you cant ssh in or get access to a terminal because of this problem you can try this

How to stop x server:
CTRL-ALT-F1
sudo /etc/init.d/gdm stop

then you can
sudo dpkg-reconfigure -p high xserver-xorg

Thanks for the help. Doing the reconfig doesn't seem to do anything, should it echo something to the screen? The problem persist irrespective....

OK. Give this a shot. If this doesn't work please also post your Xorg.0.log

CTRL + ALT + F1 to kill xserver, and then log in.

[code]

sudo apt-get remove --purge xserver-xorg

then

sudo apt-get install xserver-xorg

and finally

sudo dpkg-reconfigure xserver-xorg

then startx

[/code]

First command uninstalls xserver-xorg and purges all files (including config files)
Second command reinstalls and the Third command reconfigures.

My original answer I didn't realize xorg.conf has been depreciated as I mainly use Ubuntu server. However if there is an xorg.conf file available it will supersede any of the default settings. What you did in my first post did just that. But it was just a minimal config file. However what we are doing now will remove anything that was generated by my first post.

Hopefully this will work for you. If not please pastebin your log file Xorg.0.log and we will try and write an xorg.conf that will work for you. In the meantime I am about to watch my showtime shows i missed last night then I will be dual booting my computer that uses my HDTV as a monitor and maybe can find some settings that will work for you. If it comes down to it I will uninstall and install again using a CRT monitor and then switch to my HDTV to see if can reproduce.

I think i found the problem. I went to install today and was immediately met with problems. After cd load (flashes the black screen with pic at bottom) my display would die out on tv (check signal message) and could get no further.

Long story short. Check your bios.

Since you were previously using a CRT monitor threw VGA go into "Advanced Chipset" section and look at the "Primary Video" option. If it is on VGA there is your problem. Set to auto or the non VGA option (it was PCI-E on mine) then save bios and reboot.

If it was already set to auto go into the "Integrated Peripherals" section and "Disable" the "On-board Graphics Controller" this will disable the VGA port.

If you want to use both monitors, or just don't want to turn off the VGA port skip the "Integrated Peripherals" step and make sure "Dual Display Support" is "Enabled" Then in "Primary Video" you can try your luck with auto or choose the non VGA option, again on mine was PCI-E. Save and reboot.

Hope this gets you going! You may find your bios is setup differently but the settings should be there.

## My Working Setup (two displays)##

CRT Monitor - Connected threw VGA
Flat Screen - Connected threw HDMI

Bios-
On-board Graphics = enabled
Dual Display = enabled
Primary Video = VGA (then when I installed NVIDIA drivers I was able to set this to PCI-E and have it work.)

I realize your not trying to use two monitors. Just wanted to provide you with my working setup so if the above don't work maybe you can try that.

Our servers were down for a couple of days due to a power substation meltdown. Thanks for all your trouble, my BIOS doesn't have the same options as yours it seems. I only have options to select between PCI and AGP displays although the display is onboard... Irrespective there are no VGA options whatsoever. It doesn't matter what other remotely related options in the BIOS I mess with, the problem persists. From the xorg log file it appears to have some problem with the onboard "VIA Unichrome pro" driver. I have had enough sleepless nights with this, I am going back to installing 9.1, that worked without any problems. I managed to whack my Windows partion too, so it is going to be a major reinstall for me.

Thanks a million for all your help once a again. I might try reinstalling 10.10 again with the LCD connected, just to see if the CRT was the real cause of all the fuss. I was reluctant to do this since I had already installed a number of packages, but I have reached saturation. I'll let you know what happens.

I seem to have found the problem. 10.10 appears to have aborted the VIA Unichrome driver.