Brought this over from the bug I reported. 

I have noticed over the last few days when I am using Firefox in maximum view and have other application windows open under it, when I minimise it, it leave a ghost trail of about 3 to 4 graphical links in the top left of the screen, this happens on my laptop and my pc at work. One is using the intel GPU and the other NVIDIA, This occurs on both machines so its not related to the hardware but ubuntu 11.10 beta itself.

After FF is minimised other applications are in accessible, clicking on them does nothing, clicking randomly on the laucher sometimes works, and other times some applications are locked and can not be opened again and have to be force quit. super S also locked u, but may display one or 2 windows. It is as though the FF screen is laying over the top like a pain of glass.

I hope my explanation of the bug is understandable, and that other people too are having similar issues.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: xorg 1:7.6+7ubuntu7
ProcVersionSignature: Ubuntu 3.0.0-11.17-generic 3.0.4
Uname: Linux 3.0.0-11-generic x86_64
NonfreeKernelModules: nvidia
.proc.driver.nvidia.gpus.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 280.13 Wed Jul 27 16:53:56 PDT 2011
 GCC version: gcc version 4.6.1 (Ubuntu/Linaro 4.6.1-9ubuntu2)
.tmp.unity.support.test.0:

ApportVersion: 1.22.1-0ubuntu2
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,vpswitch,regex,animation,snap,expo,move,compiztoolbox,place,grid,imgpng,gnomecompat,wall,ezoom,workarounds,resize,fade,unitymtgrabhandles,scale,session,unityshell]
CompositorRunning: compiz
Date: Tue Sep 13 20:18:23 2011
DistUpgraded: Log time: 2011-09-12 21:34:42.825382
DistroCodename: oneiric
DistroVariant: ubuntu
DkmsStatus:
 nvidia-current, 280.13, 3.0.0-10-generic, x86_64: installed
 nvidia-current, 280.13, 3.0.0-11-generic, x86_64: installed
ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu
GpuHangFrequency: Several times a day
GpuHangReproducibility: Occurs more often under certain circumstances
GpuHangStarted: Within the last few days
GraphicsCard:
 nVidia Corporation G96 [GeForce 9600M GT] [10de:0649] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Acer Incorporated [ALI] Device [1025:0145]
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta amd64 (20110901)
JockeyStatus:
 xorg:nvidia_173 - NVIDIA accelerated graphics driver (Proprietary, Disabled, Not in use)
 xorg:nvidia_current - NVIDIA accelerated graphics driver (Proprietary, Enabled, In use)
 kmod:nvidia_173 - NVIDIA binary Xorg driver, kernel module and VDPAU library (Proprietary, Disabled, Not in use)
 kmod:nvidia_current - nvidia_current (Proprietary, Disabled, Not in use)
MachineType: Acer Aspire 8930
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-11-generic root=UUID=2528fc89-c646-498d-8dbc-b7c8fa41ec85 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UnitySupportTest: Error: command ['/usr/lib/nux/unity_support_test', '-p', '-f'] failed with exit code -11:
UpgradeStatus: Upgraded to oneiric on 2011-09-13 (0 days ago)
XorgConf:
 Section "Device"
  Identifier "Default Device"
  Option "NoLogo" "True"
 EndSection
dmi.bios.date: 12/03/2008
dmi.bios.vendor: Acer
dmi.bios.version: V1.10
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Aspire 8930
dmi.board.vendor: Acer
dmi.board.version: PSMBOU-1234567
dmi.chassis.type: 1
dmi.chassis.vendor: Acer
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnAcer:bvrV1.10:bd12/03/2008:svnAcer:pnAspire8930:pvrV1.10:rvnAcer:rnAspire8930:rvrPSMBOU-1234567:cvnAcer:ct1:cvrN/A:
dmi.product.name: Aspire 8930
dmi.product.version: V1.10
dmi.sys.vendor: Acer
version.compiz: compiz 1:0.9.5.94+bzr2803-0ubuntu1
version.ia32-libs: ia32-libs 20090808ubuntu20
version.libdrm2: libdrm2 2.4.26-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 7.11-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.11-0ubuntu3
version.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.0-1ubuntu13
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20110811.g93fc084-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.15.901-1ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110411+8378443-1