I disabled "ATI/AMD proprietary FGLRX graphics driver" by pressing "Remove" in System -> Administration -> Additional Drivers and rebooting my laptop.
Now I am already some 3rd continues hour on battery at home using wireless without any single freeze. Before it was a matter of few minutes to hang the system.
Well, my system freezing is gone.
I disabled "ATI/AMD proprietary FGLRX graphics driver" by pressing "Remove" in System -> Administration -> Additional Drivers and rebooting my laptop.
Now I am already some 3rd continues hour on battery at home using wireless without any single freeze. Before it was a matter of few minutes to hang the system.