I was using a 'Reset' Ativ S, yesterday I got me a 'fresh' one. I was having issues with my Skydrive tiles under Photos not updating. I also reformatted my microSD card on my new device, I had formatted it on my 8S before that. Later I noticed some hidden WP8 system files. Now everything works perfectly. I will keep an eye on the reboot issues I had. Maybe my new device will have less of these (because of sudden signal loss). I will, when I have time, re-install my other Ativ S, to figure out if it will still show the same problems with Skydrive.