actieons
1/ install
load Nvidia recommended driver
make dual screen with Nvidia Cenerama
Update
Reboot
with system => displays try to set de launcher on one screen
ProblemType: Crash
DistroRelease: Ubuntu 12.04
Package: gnome-control-center 1:3.4.0-0ubuntu4
ProcVersionSignature: Ubuntu 3.2.0-22.35-generic 3.2.14
Uname: Linux 3.2.0-22-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0-0ubuntu4
Architecture: amd64
CrashCounter: 1
Date: Fri Apr 6 07:58:46 2012
ExecutablePath: /usr/bin/gnome-control-center
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
ProcCmdline: gnome-control-center --overview
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: gnome-control-center
Title: gnome-control-center crashed with SIGSEGV in gtk_widget_size_allocate()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
The bug hasn't seen any activity in years and there has been no recent similar reports, the code also changed quite a lot since and it's likely the issue doesn't exist anymore. Closing, feel free to open a new report if you still get problems in recent Ubuntu versions