Comment 5 for bug 642790

most relevant packages:
ii xserver-xorg-core 2:1.9.0-0ubuntu7 Xorg X server - core server
ii xserver-common 2:1.9.0-0ubuntu7 common files used by various X servers
ii xserver-xorg-video-ati 1:6.13.1-1ubuntu5 X.Org X server -- AMD/ATI display driver wrapper
ii xserver-xorg-video-radeon 1:6.13.1-1ubuntu5 X.Org X server -- AMD/ATI Radeon display driver
ii plymouth 0.8.2-2ubuntu4 graphical boot animation and logger - main package

kernel version (uname -r):
2.6.35-22-generic

video card info (lspci -v):
01:05.0 VGA compatible controller: ATI Technologies Inc RS690 [Radeon X1200 Series] (prog-if 00 [VGA controller])
 Subsystem: ASUSTeK Computer Inc. Device 826d
 Flags: bus master, fast devsel, latency 64, IRQ 18
 Memory at f0000000 (64-bit, prefetchable) [size=128M]
 Memory at fdcf0000 (64-bit, non-prefetchable) [size=64K]
 I/O ports at de00 [size=256]
 Memory at fdb00000 (32-bit, non-prefetchable) [size=1M]
 Expansion ROM at <unassigned> [disabled]
 Capabilities: <access denied>
 Kernel driver in use: radeon
 Kernel modules: radeon