My Surface Book i7 512GB / 16GB does the very same thing shown by @AsherBerman, however it only does that after having closed the lid and going into sleep mode. Opening the lid reveals the same screen shown: smaller sized Lock Screen in from of the Desktop Login screen. Clicking, hitting Enter, dragging up, etc. can't remove it... the only thing that does remove it is Ctrl+Alt_Del - as soon as I do that, I'm at the login screen and can go on.
Then, having said that, all is OK, except that my desktop icons have been rearranged. This is the only time that happens anymore. Frustrating.
I have all updates applied. I hope this is fixed soon. I do have to say, my SB has come a long way since day one back on October 26th. The constant updates have resolved nearly every thing else for me, except mouse taps still get missed from time to time, but that's also happening on my other Windows 10 machines. Also, there's a right side area of the trackpad that seems to never register taps as a left click, maybe that area is reserved as a scroll-only zone that we can't turn off yet???
- Jim