[ubuntu] Monitor not waking up when connected with DisplayPort cable

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http://ubuntuforums.org – Hallo, I'm running Ubuntu 12.04 with latest updates on HP desktop computer with embed sandy bridge intel graphic card and onboard display port connector. The problem is that, when the monitor goes to sleep and it is connected to the display port, it will never wake up. I have to hard restart the computer. The issue in not there if the monitor is connected to the VGA port. Also I've disabled computer sleep or monitor locking but, after a while the monitor goes to sleep anyway and it never wakes up. Is someone having the same issue? The issue was not showing with Ubuntu 10.04. The installati (Hardware)