this is happening to my wife's 9550 but not mine. I am thinking that a couple of you that are suspecting intermittent electrical disconnect might be on the right path. I found a posting elsewhere about it and it could be a very simple solution...the battery cover could be a little loose and allowing the battery to come away from it's contacts. A posting elsewhere states that a person applied some tape to the inside of his battery cover and the restarting did not occur again as of 5 days after he made the fix. I know it's not ideal but it's a lot simpler to try that first rather than wiping your phone or constantly exchanging them at the store of via mail. I can't post links yet (newbie) but you can google "storm 2 9550 random restarts" and that person's blog should appear at the top of your search results. lonman6.com is his blogs url.