Hey, kapetr,
This is a well-known problem with the open source ATI driver on laptops (most notably older IBMs) running Radeon Mobility 7500. You can read plenty about it here: http://ubuntuforums.org/showthread.php?t=1285406
There are two possible fixes. One is to turn visual effects to "Normal" in System > Preferences > Appearance > Visual Effects. This has worked for some, but not for others.
If that does not work, you can enable the "vesa" driver. You will lose hardware acceleration (which I understand means more sluggish effects, lower game performance), but you will get System Monitor and notifications back. Edit /etc/X11/xorg.conf...
Code:
$ sudo gedit /etc/X11/xorg.conf
...to look like this...
Section "Device"
Identifier "Configured Video Device"
Driver "vesa"
EndSection
Section "Monitor"
Identifier "Configured Monitor"
EndSection
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
EndSection
...then reboot.
I have reported a bug about this, without results so far. https://bugs.launchpad.net/ubuntu/+s...or/+bug/440608
Hopefully one of those fixes it for you!
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