I have a Thinkpad X1 Carbon 2015 (20BSCTO1WW). Intel i5-5300U processor, 14" FHD Screen, 8GB RAM, 128GB SSD.
I'm running Wily (15.10.) I installed Wily on this machine while it was still in beta. Been keeping it updated.
The system locks up hard, seemingly at random. I've configured/tested Magic SysRq combinations, but they don't work when the system locks, and I can't switch to a terminal.
I'm not eager to do a fresh install, but can't seem to diagnose the issue.
I'm mostly looking for other diagnostic methods: the kernel goes unresponsive (doesn't panic, just freezes,) and none of the logs are showing any common thread. It happens 1-4 times per day in normal use. Seems to be related to input (ie- I've never had it happen while I wasn't directly using the machine.)
Any idea what I can try?
EDIT 2015-11-21 @ 1:00pm EST: The machine does not recover from the freeze.
EDIT 2016-02-12 @ 1:30pm EST: The issue was kernel-related. I upgraded from the 15.10 stock 4.2 kernel to one of the mainline kernels (in my case, I'm using http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-next/) and it has been running flawlessly since.