Recently my phone has been problematic. Biggest problem is that a couple times a day it will just shut itself down and restart. I've had it happen while the phone is sitting on a table, while charging and even in the middle of a call. I have reinstalled the latest t-mobile OS and it still happens. Any other thoughts on how to fix this?

I had this symptom a few months back. For me, I narrowed it down to the browser. If I left the browser on a page for too long that auto-updated itself, such as the gamecasts on ESPN, after a period of time the phone would reboot. It didn't seem to matter whether the browser was running in the foreground or background.