Still present in 1.0.42-1 of rawhide 2006-08-27.
Exact same behaviour and error message. (including line numbers)

Also present in 1.0.45-1 (tested 2006-09-27):

If s-c-d is run with no xorg.conf present, I get the error above when trying to
configure dual head:

>Traceback (most recent call last):
>  File "/usr/share/system-config-display/xConfigDialog.py", line 151, in ok
>    second_monitor = self.xconfig.monitor[1]
>IndexError: index out-of-bounds


When s-c-d is used on a working dual-head config:

>Traceback (most recent call last):
>  File "/usr/share/system-config-display/xConfigDialog.py", line 186, in ok
>    display_option = second_screen.display[0]
>IndexError: index out-of-bounds

In addition, s-c-d incorrectly reports current resolution in the "Settings" tab
(I have it set to 1600x1200, s-c-d reports 800x600) - but this is probably
because it does not autodetect my monitors(s) [Samsung SyncMaster 214T]

*** Bug 217412 has been marked as a duplicate of this bug. ***

Still exists in F7 devel, system-config-display-1.0.51-1.fc7.

On the "Dual head" tab, if I click "Use dual head" and leave Monitor Type at "No
monitor selected" and click OK I get this error on the terminal where I started
s-c-display, and the dialog box doesn't close:

  File "/usr/share/system-config-display/xConfigDialog.py", line 152, in ok
    second_monitor = self.xconfig.monitor[1]
IndexError: index out-of-bounds

If I then select "Configure..." and choose "Generic LCD Display" and "LCD Panel
1600x1200" and then click OK on the main Display Settings dialog box, I get this
error, and again the dialog box doesn't close:

Traceback (most recent call last):
  File "/usr/share/system-config-display/xConfigDialog.py", line 137, in ok
    lower_vrefresh, upper_vrefresh =
string.split(str(self.second_monitor_vrefresh), "-")
ValueError: need more than 1 value to unpack

My Settings tab:

Resolution: 1600x1200
Color Depth: Millions of Colors

My Hardware tab:

Monitor Type: (autoconfigured)
Video Card: ATI Technologies Inc RV380 [Radeon X600]

My Dual head tab:

[x] Use dual head

Second Monitor Type: LCD Panel 1600x1200
Second Video CArd: ATI Technologies Inc RV380 [Radeon X600 (PCIE)]
Resolution: 1600x1200
Color Depth: Millions of Colors
Desktop layout: Individual Desktops, or Spanning Desktops

I have two Dell 2001FP monitors connected via DVI ports to the dual-port Radeon
X600.

Update: I deleted my /etc/X11/xorg.conf, restarted s-c-display, chose "Show all
available monitors", manually selected "Dell 2001FP (Digital)" and the problem
went away and I got this config file:

# Xorg configuration created by system-config-display

Section "ServerLayout"
        Identifier     "Multihead layout"
        Screen      0  "Screen0" LeftOf "Screen1"
        Screen      1  "Screen1" 0 0
        InputDevice    "Keyboard0" "CoreKeyboard"
        Option      "Xinerama" "on"
        Option      "Clone" "off"
EndSection

Section "InputDevice"
        Identifier  "Keyboard0"
        Driver      "kbd"
        Option      "XkbModel" "pc105"
        Option      "XkbLayout" "us"
EndSection

Section "Monitor"
        Identifier   "Monitor1"
        VendorName   "Monitor Vendor"
        ModelName    "Dell 2001FP (Digital)"
        HorizSync    31.0 - 80.0
        VertRefresh  56.0 - 76.0
        Option      "dpms"
EndSection

Section "Device"
        Identifier  "Videocard0"
        Driver      "radeon"
EndSection

Section "Device"
        Identifier  "Videocard1"
        Driver      "radeon"
        VendorName  "Videocard Vendor"
        BoardName   "ATI Technologies Inc RV380 [Radeon X600 (PCIE)]"
        BusID       "PCI:1:0:0"
EndSection

Section "Screen"
        Identifier "Screen0"
        Device     "Videocard0"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
        EndSubSection
EndSection

Section "Screen"
        Identifier "Screen1"
        Device     "Videocard1"
        Monitor    "Monitor1"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes    "1600x1200"
        EndSubSection
EndSection

That config doesn't work since the BusID was specified incorrectly:

Section "Device"
        Identifier  "Videocard0"
        Driver      "radeon"
EndSection

Section "Device"
        Identifier  "Videocard1"
        Driver      "radeon"
        VendorName  "Videocard Vendor"
        BoardName   "ATI Technologies Inc RV380 [Radeon X600 (PCIE)]"
        BusID       "PCI:1:0:0"
EndSection

I got an error in the log, and the X server started in single-head, clone mode:

(WW) RADEON: No matching Device section for instance (BusID PCI:1:0:1) found

The second Device section should have been configured with:

        BusID       "PCI:1:0:1"

This is my lspci output:

01:00.0 VGA compatible controller: ATI Technologies Inc RV380 [Radeon X600 (PCIE)]
01:00.1 Display controller: ATI Technologies Inc RV380 [Radeon X600]

So I went back into s-c-display, and it defaulted back to some strange
resolution and monitor settings:

Settings:
Resolution: 800x600

Hardware:
Monitor Type: Unknown monitor

Dual head:
Second Monitor Type: No monitor selected
Resolution: 800x600

I went in to fix the monitor types again, and then changed the device for the
Second Video Card to "ATI Technologies Inc RV380 [Radeon X600]" (notice that the
description doesn't have the "(PCIE)" appended to it--this matches the second
BusID in my lspci output above).  Now it lets me select "1600x1200" on the
Settings tab, but the Dual head tab still only lets me choose "640x480" or
"800x600".

Now my /etc/X11/xorg.conf looks like this:

# Xorg configuration created by system-config-display

Section "ServerLayout"
        Identifier     "Multihead layout"
        Screen      0  "Screen0" LeftOf "Screen1"
        Screen      1  "Screen1" 0 0
        InputDevice    "Keyboard0" "CoreKeyboard"
        Option      "Xinerama" "on"
        Option      "Clone" "off"
EndSection

Section "InputDevice"
        Identifier  "Keyboard0"
        Driver      "kbd"
        Option      "XkbModel" "pc105"
        Option      "XkbLayout" "us"
EndSection

Section "Monitor"
        Identifier   "Monitor1"
        VendorName   "Monitor Vendor"
        ModelName    "Dell 2001FP (Digital)"
        HorizSync    31.0 - 80.0
        VertRefresh  56.0 - 76.0
        Option      "dpms"
EndSection

Section "Monitor"
        Identifier   "Monitor1"
        VendorName   "Monitor Vendor"
        ModelName    "Dell 2001FP (Digital)"
        HorizSync    31.0 - 80.0
        VertRefresh  56.0 - 76.0
        Option      "dpms"
EndSection

Section "Device"
        Identifier  "Videocard0"
        Driver      "radeon"
EndSection

Section "Device"
        Identifier  "Videocard1"
        Driver      "radeon"
        VendorName  "Videocard Vendor"
        BoardName   "ATI Technologies Inc RV380 [Radeon X600]"
        BusID       "PCI:1:0:1"
EndSection

Section "Screen"
        Identifier "Screen0"
        Device     "Videocard0"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes    "1600x1200" "1600x1024" "1440x900" "1400x1050"
"1360x768" "1280x1024" "1280x960" "1280x800" "1280x720" "1152x864" "1024x768"
"800x600" "640x480"
        EndSubSection
EndSection

Section "Screen"
        Identifier "Screen1"
        Device     "Videocard1"
        Monitor    "Monitor1"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes    "800x600"
        EndSubSection
EndSection

Why are there two Monitor sections with an Identifier of "Monitor1"?  Something
is rotten in Denmark...

no activity in a year, RAWHIDE seems to work, closing bug