Forwarding this bug from Ubuntu reporter Patrik:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/567517

[Problem]
Sporadically while scrolling in any application the screen in most parts would change to "static" noise.

[Original Description]
scrolling in evolution (reproducible until a few days ago, now not anymore) or in firefox or chrome some times most parts of the screen would suddenly switch to "repeating patterns of noise". when moving the mouse, a huge square of noise moves across the screen... I guess this is related to some part of the display system... but which I don't know.

DistroRelease: Ubuntu 10.04
Package: xorg 1:7.5+5ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic x86_64
Architecture: amd64
CheckboxSubmission: ee8175d50c9365fb4e14953b48e703a7
CheckboxSystem: e884839b1147d494b3cc922c5deb0043
Date: Tue Apr 20 22:37:03 2010
DkmsStatus: Error: [Errno 2] No such file or directory
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Beta amd64 (20100318)
MachineType: Packard Bell DOTMA
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-21-generic root=UUID=271fc275-3ae6-4d35-89cb-3c6b2202d6d2 ro quiet splash
ProcEnviron:
 LANG=de_CH.utf8SourcePackage: xorg
dmi.bios.date: 07/30/2009
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: v1.3302
dmi.board.name: SJM11-YK
dmi.board.vendor: Packard Bell
dmi.board.version: Not Applicable
dmi.chassis.type: 10
dmi.chassis.vendor: Packard Bell
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrv1.3302:bd07/30/2009:svnPackardBell:pnDOTMA:pvrNotApplicable:rvnPackardBell:rnSJM11-YK:rvrNotApplicable:cvnPackardBell:ct10:cvrN/A:
dmi.product.name: DOTMA
dmi.product.version: Not Applicable
dmi.sys.vendor: Packard Bell
glxinfo: Error: [Errno 2] No such file or directory
system: codename:           lucid
 architecture:       x86_64
 kernel:             2.6.32-21-generic