I occasionally have similar symptoms on my Dell E6420 with Sandy Bridge graphics. As a workaround, it helps to log in via console or ssh and kill the screensaver process.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/827531 Title: intel sandy bridge: X session sometimes unrecoverable after screensaver/display powersafe To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/827531/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
