Sorry, I do not have a solution, but a very similar situation that just started last week.
I have been working on this laptop for about 2 years without issue.
Starting about 5 days ago i noticed if i got up and stepped away from my computer, when i came back it had rebooted. I would have the welcome screen and when i logged in all the windows I had up when i left would be gone; when i started up chrome it would ask if i wanted to restore tabs, etc. So my laptop is now rebooting 3-4 times a day.
I caught it in the act once, i was sitting on the couch but could see the screen. All of a sudden a cmd window popped open briefly, then disappeared, and then the blue screen appeared. The message says 'your PC ran into a problem and needs to restart. We're collecting info and then we'll restart for you...' Stop Code: SYSTEM_SERVICE_EXCEPTION. Then it reboots after it hits 100%.
Another time, i was walking back into my office after stepping away and the blue screen was there, and then it rebooted.
This has not occurred once while i am sitting working actively at my computer, only when i stop and step away for some period of time. Since I use this for work I am on using it almost all day.
Apologies if this post is out of place, if i should start a stand alone question let me know and i will do so.
OS Name Microsoft Windows 10 Pro
Version 10.0.14393 Build 14393
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Manufacturer LENOVO
System Model 20BX001MUS
System Type x64-based PC
System SKU LENOVO_MT_20BX_BU_Think_FM_ThinkPad T450s
Processor Intel(R) Core(TM) i7-5600U CPU @ 2.60GHz, 2594 Mhz, 2 Core(s), 4 Logical Processor(s)
BIOS Version/Date LENOVO JBET68WW (1.32 ), 2/27/2018
SMBIOS Version 2.7
Embedded Controller Version 1.04
BIOS Mode UEFI
Found the Event Log:
Level Date and Time Source Event ID Task Category
Critical 7/25/2018 13:56 Kernel-Power 41 -63
Critical 7/25/2018 13:31 Kernel-Power 41 -63
Critical 7/25/2018 11:31 Kernel-Power 41 -63
Critical 7/24/2018 16:13 Kernel-Power 41 -63
Critical 7/24/2018 14:49 Kernel-Power 41 -63
Critical 7/24/2018 11:07 Kernel-Power 41 -63
Critical 7/24/2018 8:27 Kernel-Power 41 -63
Critical 7/24/2018 7:42 Kernel-Power 41 -63
Critical 7/23/2018 19:44 Kernel-Power 41 -63
Critical 7/23/2018 17:25 Kernel-Power 41 -63
Critical 7/23/2018 16:43 Kernel-Power 41 -63
Critical 7/23/2018 14:22 Kernel-Power 41 -63
Critical 7/23/2018 12:59 Kernel-Power 41 -63
Critical 7/23/2018 12:15 Kernel-Power 41 -63
Critical 7/23/2018 11:52 Kernel-Power 41 -63
Critical 7/23/2018 10:51 Kernel-Power 41 -63
Critical 7/23/2018 10:24 Kernel-Power 41 -63
Critical 7/22/2018 21:49 Kernel-Power 41 -63
Critical 7/22/2018 21:38 Kernel-Power 41 -63
Critical 7/22/2018 20:56 Kernel-Power 41 -63
Critical 7/22/2018 17:08 Kernel-Power 41 -63
Critical 7/22/2018 10:58 Kernel-Power 41 -63
Critical 7/22/2018 10:16 Kernel-Power 41 -63
Critical 7/22/2018 9:36 Kernel-Power 41 -63
Critical 7/22/2018 8:48 Kernel-Power 41 -63
Critical 7/21/2018 21:10 Kernel-Power 41 -63
Critical 7/21/2018 19:00 Kernel-Power 41 -63
Critical 6/24/2018 21:49 Kernel-Power 41 -63
Critical 6/3/2018 19:09 Kernel-Power 41 -63
Critical 4/18/2018 17:01 Kernel-Power 41 -63