I started to have exactly the same problem on my new HP laptop, complete UI and peripheral freeze. By just pulling out the power cord, the system instantly becomes responsive again and I can continue work normally. It won't appear again until next reboot, always randomly. I always find a vgaarb error in everything.log at the very moment of the lockup :
Feb 9 08:03:47 hp2 kernel: [70005.222588] vgaarb: this pci device is not a vga device The above line is also logged without any system freeze. I wish to know if the trick works for you, please update. Cheers.
