I had a problem with my phone resetting itself but it was a special circumstance. It was the 4th of July and I was at a park to watch the fireworks. I should have been getting 3G but I guess with the tons of people in the park with their cell phones I just couldn't keep a good signal. I tried to send a text message and it kept failing then my phone was being stupid and it was resetting itself a lot.
So, I just powered it off and took a look at it when I got home and it has been fine since.
So, I wonder if the phone just has issues when it can't keep a signal?