On boot up of the system a black screen is displayed when it should be the login screen.

SUSE Linux Enterprise Desktop 11

ATI  proprietary fglrx driver is installed (even if it is not being used).

The nVidia proprietary driver "nvidia" can also cause some unexpected problems.  See the Additional Information at the bottom.

If the ATI proprietary fglrx driver is installed it can cause all other graphics drivers to fail with a black screen when the X server is started and the graphic login screen (displaymanager) should be displayed.

This problem will generally be noticed if for some reason the fglrx driver fails at some point.  For example, if an update to the driver is installed but ATI has removed support for the card that is installed (it would have to be an older one) then the X server may fail.  Attempting to run sax2 to change the driver will likely fail as described here.

Installation of the ATI fglrx driver makes changes to the X server that are not compatible with other drivers.

To fix the problem all that needs to be done is to uninstall the fgrlx packages.  This can be done from the command line (since the X server is down) with the "zypper" command.

First step is to get booted up in text only mode also referred to as "runlevel 3".  To do this, reboot the system and when the GRUB menu comes up (where you select to boot SUSE Linux Enterprise Desktop 11) just verify that "SUSE Linux Enterprise Desktop 11" is highlighted and then type in the number 3.  The "3" will show up in the Boot Options below the selections.  It should be at the end of the line if there are any other options listed.  Once the number 3 is at the end of that line just press Enter to boot.

You will be brought to a text screen with a login prompt.  Type in "root" and press Enter and then enter the root users password when requested.

Use the zypper command to view the installed fglrx packages:

zypper se fglrx

This should display something similar to the following:

S | Name                     | Summary                                     | Type  
--+--------------------------+---------------------------------------------+--------
  | ati-fglrxG01-kmp-debug   | ATI "fglrx" driver kernel module            | package
  | ati-fglrxG01-kmp-default | ATI "fglrx" driver kernel module            | package
i | ati-fglrxG01-kmp-pae     | ATI "fglrx" driver kernel module            | package
  | ati-fglrxG01-kmp-trace   | ATI "fglrx" driver kernel module            | package
i | x11-video-fglrxG01       | X Window display driver for the ATI graphics| package

The "i" indicates that this package is installed.  To remove the two packages just use the "zypper rm" command followed by the packages you wish to remove, like this (remember it is case sensitive):

zypper rm ati-fglrx-G01-kmp-pae x11-video-fglrxG01

The zypper program will ask for confirmation to remove these packages.  Once removed you can then run the appropriate sax2 command to identify and configure a new graphics driver.  For example, if the open source driver for ATI (which is the "radeon" driver) is the correct choice then the sax2 command would be as follows:

sax2 -r -m 0=radeon

The graphic configuration screen will be loaded.  Select the option to Change Configuration and verify that the monitor and resolution settings are appropriate before saving.

Other drivers that could be considered are "fbdev" and"vesa".  These drivers work for almost all graphics cards.  You can select these by replacing the "radeon" driver with the "fbdev" or "vesa" driver in the "sax2 -r -m 0=radeon" command described above.

Once the system is configured for the new driver you are ready to start the X server and associated programs.  Runlevel 5 is the runlevel that has the graphics enabled.  Since the system is now in runlevel 3, the command "init 5" can be entered to switch to runlevel 5.  After entering the "init 5" command the graphic login screen should be displayed.  Alternatively, the system can be rebooted to enable the graphics mode.

The "nvidia" proprietary driver can also cause some odd problems with the attempt to use other drivers such as the nVidia open source driver "nv" or others such as "fbdev" or "vesa".  Use these same steps to remove the packages associated with the "nvidia" driver before configuring the nv, fbdev, or vesa drivers with sax2.