Hi, Can you update ThinkPad T420 BIOS to at least version 1.39, Version: 83ET69WW (1.39 ), then have a try to enable x2apic.
Thanks -Youquan -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/922037 Title: "reduce brightness" key freezes system To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/922037/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
