When I had my 8703e from Alltel, I would notice it re-booting every once in a while. I could be at my desk, with the Blackberry sitting there, and it would re-boot. Not running anything at the time.
It would usually happen when I was in my office, which is in the basement of our building. Coverage is good, so that wasnt the issue. \
I thought it was just me having this.