Hi there, I'm a Linux newbie, hope someone can give me a hand. Recently I partitioned my harddisk to run both Ubuntu and XP. Then I installed KDE on my Ubuntu Desktop. Everything runs smoothly, until today I made the following changes: (1) set desktop to use dual-monitor (under the "system settings") (2) modified /etc/fstab and added a new line like this: /dev/sda8 /media/sda8 ext3 defaults 0 2 and then reboot. Then, when I select to boot this partition, the Ubuntu startup screen appears, after some time of loading, a black screen appears, and then the system stops here. I am not sure where goes wrong. How could I fix this? Thanks for help.

To get some simple diagnostics, let's try to boot with the splash screen and "quiet boot" turned off. Newer versions of Ubuntu have a "recovery" boot option that you may try. If that's not available and your installation is using GRUB, you can do so by selecting your normal boot option and hitting "e" to edit the boot command line. Now select the line the begins with "kernel" and hit "e" again. Remove the "quiet" and "splash" options. Press return and then hit "b" to boot as edited. You may also add the "single" option to boot into single user mode (the recovery option does this; single user mode should nearly always boot). None of these changes are permanent, so don't worry about messing anything up.

Let us know how it goes and what output you see.

I guess it's your monitor setting.

Run in recovery mode.
$sudo vim /etc/X11/xorg.conf //open your graphics settings in the vim-text editor

And then the fun part begins ... you have to remove the "dual screen"-settings.
Sadly I don't know them ...

go to the Device-Section which sounds like your graphics card
Mine:
--
Section "Device"
Identifier "ATI Technologies Inc Radeon Mobility X700 (PCIE)"
Driver "fglrx"
BoardName "ati"
Option "VideoOverlay" "on"
Option "OpenGLOverlay" "off"
BusID "PCI:3:0:0"
EndSection
--

- Delete everything but the identifier, driver, boardname and busID
- As for the "Option"s.Delete the ones that might be connected to your dual screen stuff ( I cannot be more accurate sorry :( )

@Note: You can delete lines by doing "dd" on the line
You can switch to the writing mode by pressing "i" (like insert) and you leave it again by pressing escape. You can remove single characters with backspace and delete.
You can always press escape (multiple times) to go into the "standard mode" of vim.


Next:
Check the "extension" and "serverflag2 parts of this file.
Mine:
--
Section "Extensions"
Option "Composite" "0"
EndSection

Section "ServerFlags"
Option "AIGLX" "off"
EndSection
--
- Again if something looks like it's connected to dualscreening. Delete it.



Try it out. Hope it helps.

I fixed it by booting in recovery mode and then execute the command

sudo dpkg-reconfigure -phigh xserver-xorg

to auto-update the etc/X11/xorg.conf file.

It works again now. Thanks very much.