[Lucid Beta1] hmu-002 testcases failed Two vertical lateral white strips comes up when creating a new folder/file/object on Desktop

Binary package hint: xserver-xorg-video-ati

Very strange behaviour.

Steps to reproduce:
1) Boot from a live CD/USB
2) Right click with mouse on desktop->Create Folder/create Document(empty file).
3) Just after that, when the focus is on the name of the folder/file, two vertical lateral white strips (left and right) comes up on the background, and they vanish only logging out and in again. Changing background doesn't change anything, it seems to be a video driver issue.

Two screenshot attached, one before, and one after creating a folder.

ProblemType: Bug
Architecture: i386
Date: Thu Mar 18 20:58:54 2010
DistroRelease: Ubuntu 10.04
DkmsStatus: Error: [Errno 2] No such file or directory
GdmLog1: Error: command ['gksu', '-D', 'Apport', '--', 'cat', '/var/log/gdm/:0.log.1'] failed with exit code 1: cat: /var/log/gdm/:0.log.1: No such file or directory
GdmLog2: Error: command ['gksu', '-D', 'Apport', '--', 'cat', '/var/log/gdm/:0.log.2'] failed with exit code 1: cat: /var/log/gdm/:0.log.2: No such file or directory
LiveMediaBuild: Ubuntu 10.04 "Lucid Lynx" - Beta i386 (20100318)
MachineType: Acer TravelMate 6593
Package: xserver-xorg-video-ati 1:6.12.191-1ubuntu2
PccardctlIdent:
 Socket 0:
   no product info available
 Socket 1:
   product info: "O2Micro", "SmartCardBus Reader", "V1.0", ""
   manfid: 0xffff, 0x0001
PccardctlStatus:
 Socket 0:
   no card
 Socket 1:
   5.0V 16-bit PC Card
   Subdevice 0 (function 0) [unbound]
ProcCmdLine: BOOT_IMAGE=/casper/vmlinuz noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/hostname.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
ProcEnviron:
 LANG=it_IT.utf8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-16.25-generic
SourcePackage: xserver-xorg-video-ati
Uname: Linux 2.6.32-16-generic i686
dmi.bios.date: 08/14/2008
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: V1.04
dmi.board.name: FourPeaks
dmi.board.vendor: Acer
dmi.board.version: Rev
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrV1.04:bd08/14/2008:svnAcer:pnTravelMate6593:pvr0100:rvnAcer:rnFourPeaks:rvrRev:cvnAcer:ct10:cvrN/A:
dmi.product.name: TravelMate 6593
dmi.product.version: 0100
dmi.sys.vendor: Acer
glxinfo: Error: [Errno 2] No such file or directory
system:
 distro: Ubuntu
 codename: lucid
 architecture: i686
 kernel: 2.6.32-16-generic