I have the same problem.
Phone started rebooting intermittently for about a week.
Did a reset, then it got stuck in reboot loop.
Took to the store, and of course it let them activate.
But then it started to have the problem. So they sent me out a new one.
Got the new one. Same problem....RIGHT OUT OF THE BOX.
Could not even activate.
Went to the store, and of course it let them activate.
So, told them I'd try the phone for a day or so. Took it home.
Two hours late, SAME DEAL. Reboot loop. Took to store, and of course it started working again.
They did a reset, and were able to reproduce the problem. So, they sent me a new one.
Will pick up the new one today, and see what happens.
Getting frustrated with this stupid phone.