Total freeze when trying to run two screens (not mirrored)

[bosy]

Binary package hint: firefox-3.5

System becomes completely unresponsive when I try to change from mirrored screens to seperate screens.
I run Ubuntu 9.10 with all updates for x64.
Regards Bo

ProblemType: Bug
Architecture: amd64
Date: Thu Nov 5 07:58:20 2009
DistroRelease: Ubuntu 9.10
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
Package: firefox-3.5 3.5.4+nobinonly-0ubuntu0.9.10.1
ProcEnviron:
 LANG=sv_SE.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-14.48-generic
SourcePackage: firefox-3.5
Uname: Linux 2.6.31-14-generic x86_64
XsessionErrors:
 (polkit-gnome-authentication-agent-1:1736): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed
 (nautilus:1728): Eel-CRITICAL **: eel_preferences_get_boolean: assertion `preferences_is_initialized ()' failed
 (gnome-display-properties:2188): Gtk-WARNING **: Ignoring the separator setting
 (gnome-display-properties:2188): Gtk-WARNING **: No object called:

[bosy (bo-stanley)]

This bug is NOT connected in anyway to Firefox.