Same problem here - I've done the restarts (5 times in 3 days), the full restore, etc. but it comes back. But I found this thread (http://discussions.apple.com/thread.jspa?messageID=12595197#12595197) where apparently doing a Restore All Settings under Settings\General seemed to work for a user named robbbb1. Trying it now. Fingers crossed.
My phone is doing the same thing!!!
I have to restart a couple of times daily,
I have reset and restored it.
I have even taken it back to the Apple Store, they switched out the phone Claiming it was Hardware issues.
I was home free for a little over a week then it started happening again. Someone PLEASE HELP!!!