Since a few days I have the most annoying effect that reboots (e.g. after installing some upgrade) hang. The system shuts down, the Surface logo comes up again, but then the rotating dots never appear and the process hangs there. I then always have to power this beast off (by pressing the power button >= 10 seconds or so until the device shuts off. Subsequent reboots then always worked fine, but I am getting a bit nervous: why or what is a normal restart blocking/hanging/crashing? Any idea how to diagnose this?