Comment 3 for bug 412113

similar issue here:

X.Org X Server 1.6.0
Release Date: 2009-2-25
X Protocol Version 11, Revision 0
Build Operating System: Linux 2.6.24-23-server i686 Ubuntu
Current Operating System: Linux ntp-dp 2.6.28-15-server #49-Ubuntu SMP Tue Aug 18 19:30:06 UTC 2009 i686
Build Date: 09 April 2009 02:10:02AM
xorg-server 2:1.6.0-0ubuntu14 (<email address hidden>)
Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Mon Aug 24 12:21:13 2009
(==) Using config file: "/etc/X11/xorg.conf"
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning: Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
> Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning: Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
> Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning: Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
> Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning: Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
> Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning: Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
> Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server

Backtrace:
0: /usr/X11R6/bin/X(xorg_backtrace+0x3b) [0x813518b]
1: /usr/X11R6/bin/X(xf86SigHandler+0x55) [0x80c7be5]
2: [0xb7f2a400]
Saw signal 11. Server aborting.
ddxSigGiveUp: Closing log
ddxSigGiveUp: re-raising 11