My Exhibit 2 is less than a month old. I like it in all respects except one -- there are times when it starts vibrating and just won't stop. I either have to turn it off or take the battery out to make it stop. It seems to happen only when I am on wifi. It is unclear what triggers this. At least once, it seemed to be triggered by an incoming email. Is there a way to disable email notification (so that it doesn't vibrate)? Any other suggestions for fixing this?