Some days ago, I installed Ubuntu 12.04. Since I wanted to use dualview using an external display I installed the propriatary AMD Catalyst 12.4. The graphics are fine, but if I run the updates found by the updates manager, Ubuntu won't be able to start with graphics after reboot. I installed Ubuntu 3 times until I realized what the problem was. So now I got the basic installation with Catalyst running but I can't update the system. Is there any solution to this? Or can I somehow identify which update causes this? My System is a Lenovo y560 Ideapad (Intel Core i7, 8GB RAM, with AMD Radeon HD 6570M/5700 Series. Thank you in advance