After come back to screesaver the window manager freezes sometime

Binary package hint: xorg

juste after come back to screesaver the window manager freezes sometime about every 10-20sec

Linux redhome 2.6.32-25-generic #44-Ubuntu SMP Fri Sep 17 20:05:27 UTC 2010 x86_64 GNU/Linux
Description: Ubuntu 10.04.1 LTS
Release: 10.04
Package: xorg
Status: install ok installed
Priority: optional
Section: x11
Installed-Size: 36
Maintainer: Ubuntu X-SWAT <email address hidden>
Architecture: amd64
Version: 1:7.5+5ubuntu1
Provides: x-window-system, x-window-system-core
Depends: xserver-xorg, libgl1-mesa-glx | libgl1, libgl1-mesa-dri, libglu1-mesa, xfonts-base (>= 1:1.0.0-1), xfonts-100dpi (>= 1:1.0.0-1), xfonts-75dpi (>= 1:1.0.0-1), x11-apps, x11-session-utils, x11-utils, x11-xfs-utils, x11-xkb-utils, x11-xserver-utils, xauth, xinit, xfonts-utils, xkb-data, xorg-docs-core, xterm | x-terminal-emulator, x11-common, xinput
Recommends: xfonts-scalable (>= 1:1.0.0-1)
Suggests: xorg-docs
Description: X.Org X Window System
 This metapackage provides the components for a standalone
 workstation running the X Window System. It provides the X libraries, an X
 server, a set of fonts, and a group of basic X clients and utilities.
 .
 Higher level metapackages, such as those for desktop environments, can
 depend on this package and simplify their dependencies.
 .
 It should be noted that a package providing x-window-manager should also
 be installed to ensure a comfortable X experience.
Original-Maintainer: Debian X Strike Force <email address hidden>
Package: xorg
Priority: optional
Section: x11
Installed-Size: 36
Maintainer: Ubuntu X-SWAT <email address hidden>
Original-Maintainer: Debian X Strike Force <email address hidden>
Architecture: amd64
Version: 1:7.5+5ubuntu1
Provides: x-window-system, x-window-system-core
Depends: xserver-xorg, libgl1-mesa-glx | libgl1, libgl1-mesa-dri, libglu1-mesa, xfonts-base (>= 1:1.0.0-1), xfonts-100dpi (>= 1:1.0.0-1), xfonts-75dpi (>= 1:1.0.0-1), x11-apps, x11-session-utils, x11-utils, x11-xfs-utils, x11-xkb-utils, x11-xserver-utils, xauth, xinit, xfonts-utils, xkb-data, xorg-docs-core, xterm | x-terminal-emulator, x11-common, xinput
Recommends: xfonts-scalable (>= 1:1.0.0-1)
Suggests: xorg-docs
Filename: pool/main/x/xorg/xorg_7.5+5ubuntu1_amd64.deb
Size: 1498
MD5sum: ba60ebf4e4960702451cd2c769913c2d
SHA1: 810c06f9bbb88cd94cee77840082ca83e31aefec
SHA256: c17d707ba1886510be5a83155734ced4989aec9332382af8e925af2c0965cec2
Description: X.Org X Window System
 This metapackage provides the components for a standalone
 workstation running the X Window System. It provides the X libraries, an X
 server, a set of fonts, and a group of basic X clients and utilities.
 .
 Higher level metapackages, such as those for desktop environments, can
 depend on this package and simplify their dependencies.
 .
 It should be noted that a package providing x-window-manager should also
 be installed to ensure a comfortable X experience.
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Origin: Ubuntu
Supported: 3y
Task: ubuntu-desktop, kubuntu-desktop, kubuntu-netbook, edubuntu-desktop, xubuntu-desktop, mythbuntu-backend-master, mythbuntu-backend-slave, mythbuntu-desktop, mythbuntu-frontend, ubuntu-netbook

xorg:
  Installé : 1:7.5+5ubuntu1
  Candidat : 1:7.5+5ubuntu1
 Table de version :
 *** 1:7.5+5ubuntu1 0
        500 http://ch.archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: xorg 1:7.5+5ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-25.44-generic 2.6.32.21+drm33.7
Uname: Linux 2.6.32-25-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Thu Sep 30 22:18:45 2010
MachineType: System manufacturer System Product Name
ProcCmdLine: root=/dev/md0 ro quiet splash
ProcEnviron:
 LANGUAGE=fr_CH:fr
 LANG=fr_CH.UTF-8
 SHELL=/bin/bash
SourcePackage: xorg
dmi.bios.date: 10/14/2008
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 0801
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: P5K64 WS
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0801:bd10/14/2008:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP5K64WS:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: System Product Name
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
system:
 distro: Ubuntu
 codename: lucid
 architecture: x86_64
 kernel: 2.6.32-25-generic