Desinstalar Ati Radeon HD 6700 M

$ sudo sh /usr/share/ati/fglrx-uninstall.sh
$ sudo apt-get remove --purge fglrx fglrx_* fglrx-amdcccle* fglrx-dev* 
 $ sudo apt-get remove --purge xserver-xorg-video-ati xserver-xorg-video-radeon
$ sudo apt-get install xserver-xorg-video-ati
$ sudo apt-get install --reinstall libgl1-mesa-glx:i386 libgl1-mesa-glx:amd64 libgl1-mesa-dri:i386 libgl1-mesa-dri:amd64 xserver-xorg-core