Ubuntu Alpha 4 would not display anything on my ACER Travelmate system using an ATI Mobility Radeon X700 graphic card.
The issue was related to the migration to XServer 1.6 and the proprietary driver from ATI not supporting Xserver 1.6.
Doing this sequence to install open source driver instead restored my system !
1. sudo apt-get remove –purge fglrx*
2. sudo apt-get remove –purge xserver-xorg-video-ati xserver-xorg-video-radeon
3. sudo apt-get install xserver-xorg-video-ati
4. Restart.
