This problem still Presist in Ubuntu 14.04 (fully updated as of today). I have Lenovo W520 running Ubuntu 14.04 and NVIDIA Corporation GF108GLM [Quadro 1000M]. Anything that tries to change brightness can freeze the system, but only if running in Discrete Graphics Mode (in BIOS). I need Discrete mode to run multi-monitor setup.
Workaround I am currently using successfully is to disable Vt-d through bios (as others suggested). But this is limiting my system's capability to effectively utilize visualization technologies. Please fix this. (Please let me know if I can be of any help in this regard). -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/776999 Title: [Lenovo W520] laptop freezes on ACPI-related actions To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/776999/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
