Xorg freeze

Binary package hint: xorg

I have encountered the problem three times in 20 minutes. While working with just firefox, without any flash sites open (if that matters), and audacious playing internet radio, the UI just freezes. I am no longer able to use the mouse or the keyboard. I also could not switch to another terminal with Ctrl+Alt+F(x) or Alt+F(x)

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: xorg 1:7.5+5ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-27.49-generic 2.6.32.26+drm33.12
Uname: Linux 2.6.32-27-generic x86_64
NonfreeKernelModules: fglrx
Architecture: amd64
Date: Tue Dec 28 18:23:37 2010
DkmsStatus: fglrx, 8.723.1, 2.6.32-27-generic, x86_64: installed
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
MachineType: Dell Inc. Studio XPS 1647
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-27-generic root=UUID=d0cc95d2-177c-4b5c-888b-a650075fbd2a ro quiet splash
ProcEnviron:
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
dmi.bios.date: 12/18/2009
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A01
dmi.board.name: 0W61J1
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A01
dmi.modalias: dmi:bvnDellInc.:bvrA01:bd12/18/2009:svnDellInc.:pnStudioXPS1647:pvrA01:rvnDellInc.:rn0W61J1:rvrA01:cvnDellInc.:ct8:cvrA01:
dmi.product.name: Studio XPS 1647
dmi.product.version: A01
dmi.sys.vendor: Dell Inc.
glxinfo: Error: [Errno 2] No such file or directory
system:
 distro: Ubuntu
 codename: lucid
 architecture: x86_64
 kernel: 2.6.32-27-generic