This might be a duplicate of  Issue 614042 .
Does this only happen when tapping a lock/power button, or is there another trigger?

I tried  Issue 614042  and was able to recreate it. 
But what I find is if I wait enough long even without me touching it will go to the bottom. I use the screen keep on plug in and usually leave home for a while and when I go back it's already at the bottom. 

Just updated to 52.0.2743.32, 614042 is fixed, but before waiting for more hours I cannot tell if this bug is fixed too. 

Thanks, keep me posted. I'm hoping the two issues had the same root cause.

Thank you for providing more feedback. Adding requester "msw@chromium.org" for another review and adding "Needs-Review" label for tracking.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

 Issue 620812  has been merged into this issue.

#CBC-RS/TC-watchlist

Please lmk if anyone encounters this defect on M-52 (after #396599 / 136633328b3c7b2f46be0fe238644191922a80b7)
I believe this issue is fixed for M-52 and later, but the fix was rejected for merge to M-51 in  Issue 614042 .
I'll leave this open for a while to dup M-51 bug reports and await any reports of repro on M-52.

( the M-52 merge commit is https://chromium.googlesource.com/chromium/src/+/136633328b3c7b2f46be0fe238644191922a80b7 )

I got a chance to leave my laptop on for two days and it seems the problem never happened again. I will bring more update if it does in the future. 

Thanks for circling back; I'm glad to hear this is very likely fixed.

Thanks to a Chromebook Central user I think we have found the reproducible cause of the bug: Hitting Backspace + Power button. I get the exact results of the bug: shelf moves from side to the bottom and can't be moved again without a reboot. This happens with current stable:

Google Chrome	51.0.2704.103 (Official Build) (64-bit)
Revision	0
Platform	8172.60.0 (Official Build) stable-channel quawks

Tried Backspace+Power button, problem not found on the Beta channel. 

Version 52.0.2743.41 beta (64-bit)
Platform 8350.31.0 (Official Build) beta-channel peppy
Firmware Google_Peppy.4389.93.0

I can confirm: By Hitting Backspace + Power button, I get the exact results of the bug: shelf moves from side to the bottom and can't be moved again without a locking screen or rebooting. This happens with:

Version 51.0.2704.103 (64-bit)
Platform 8172.60.0 (Official Build) stable-channel peppy
Firmware Google_Peppy.4389.93.0

I first noticed this behavior after connecting/disconnecting an external display. Not sure if this clue helps, could have just been coincidence.

This key combination is Backspace +_ 

The key combination is Backspace + Lock (Keypad) on ASUS Flip.

An annoying "fat finger" triggered bug...

Version 51.0.2704.106
Platform 8172.62.0 (Official Build) stable-channel veyron_minnie
Firmware Google_Veyron_Minnie.6588.197.0

Asus C100P (Flip)

Can reproduce by fatfingering Backspace+Lock, but not by Backspace+-

Can reset by Sign Out and sign back in. 

Chrome Os 53.02785.55/8530.49.0 cyan