4 July 2013:
!@#$%^& The new phone did it this morning. A restart followed by restarts at regular intervals. There is one thing though: the magnetic case. My original phone was fine at the start. It didn’t experience the restart issues until later. I also didn’t have the particular case when I got the orignal phone. I only got the case it a few weeks later around the time the restart issues started.
9 July 2013:
I know it’s hard to believe but the magnetic clip(s) on the case caused the issues I had. I haven’t had a single random restart since 4 July 2013.