It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

×
Windows 10, playing in Windowed mode (1280x720)
Game crashes when I do the Windows Lock Screen (force of habit when I leave my computer on the table so the kids/cat don't hit random keys and delete my 'work'...)

Log file indicates (which isn't surprising) that the Graphics Device was lost..

"HandleD3DDeviceLost
HandleD3DDeviceLost: still lost
Skipped frame because GfxDevice is in invalid state (device lost)"