[Karmic] screen corruption with Radeon Mobility 7500 1002:4c57

Binary package hint: xserver-xorg-video-ati

The probleme appear with the system-manager and NotifyOSD with an ibm t42.
My video cart use XAA because of low memory probleme, so I try with EXA and the problem disappear (but other come).You can look at the print-screen.
Have a nice day and don't hesitate for other question.
jb

ProblemType: Bug
Architecture: i386
Date: Mon Sep 28 19:31:30 2009
DistroRelease: Ubuntu 9.10
MachineType: IBM 2374K1G
Package: xserver-xorg-video-ati 1:6.12.99+git20090825.fc74e119-0ubuntu2
PccardctlIdent:
 Socket 0:
   no product info available
 Socket 1:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
 Socket 1:
   no card
ProcCmdLine: root=UUID=272fe164-c2c9-448f-950b-fe6369af86ea ro quiet splash
ProcEnviron:
 LANGUAGE=fr_FR.UTF-8
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-11.36-generic
RelatedPackageVersions:
 xserver-xorg 1:7.4+3ubuntu5
 libgl1-mesa-glx 7.6.0~git20090817.7c422387-0ubuntu6
 libdrm2 2.4.13-1ubuntu1
 xserver-xorg-video-intel 2:2.8.1-1ubuntu2
 xserver-xorg-video-ati 1:6.12.99+git20090825.fc74e119-0ubuntu2
SourcePackage: xserver-xorg-video-ati
Uname: Linux 2.6.31-11-generic i686
dmi.bios.date: 03/29/2005
dmi.bios.vendor: IBM
dmi.bios.version: 1RETDJWW (3.15 )
dmi.board.name: 2374K1G
dmi.board.vendor: IBM
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: IBM
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnIBM:bvr1RETDJWW(3.15):bd03/29/2005:svnIBM:pn2374K1G:pvrThinkPadT42:rvnIBM:rn2374K1G:rvrNotAvailable:cvnIBM:ct10:cvrNotAvailable:
dmi.product.name: 2374K1G
dmi.product.version: ThinkPad T42
dmi.sys.vendor: IBM
fglrx: Not loaded
system:
 distro: Ubuntu
 architecture: i686kernel: 2.6.31-11-generic