This sounds like compiz causing a DRI crash. Try disabling "Desktop effects" or add
Option "DRI" "off"
to the Device section of xorg.conf
However I also saw some garbage in your log:
II) RADEON(0): v_active: 800 v_sync: 802 v_sync_end 808 v_blanking: 823 v_border: 0
(II) RADEON(0): CD516154W01
(II) RADEON(0): .>LWz折
(II) RADEON(0): EDID (in hex):
This sounds like compiz causing a DRI crash. Try disabling "Desktop effects" or add
Option "DRI" "off"
to the Device section of xorg.conf
However I also saw some garbage in your log:
II) RADEON(0): v_active: 800 v_sync: 802 v_sync_end 808 v_blanking: 823 v_border: 0
(II) RADEON(0): CD516154W01
(II) RADEON(0): .>LWz折
(II) RADEON(0): EDID (in hex):