Samsung Galaxy S2 — phone restarts after shut off

Hello all, I've scoured this forum, and the net in general, and cannot find any information on this. I've downloaded a good number of apps, let's say 50 maximum, and only recently have I started experiencing this issue. All of these apps were readily found on the marketplace, ie. Angry Birds, FB, USAA, FML, Google+, Skype, etc. Now, recently, as the title of the thread will state, when I shut off my phone, it will start itself up again after a maximum observed period of about 5 minutes, most times it will start back up within a minute of me shutting it off. I have just completed a hard factory reset of my phone, and I am running Android version 2.3.6. The only things I have done to the phone thus far after the reset are to sync my contacts with the phone and set up the email accounts I have. I shut my phone off to see if the reset worked, and it seemed fine until about 10 minutes later it mysteriously started up again on it's own, sitting next to me. The only conclusions I have come to are 1) my phone is corrupted beyond what a factory reset will do, in which case i'll have to take it to my local Sprint Store and have them check it out/ replace it if possible, and 2) Someone has hijacked my phone remotely and is continuously monitoring me through my phone, and keeps the link active by turning it back on when it's powered down. Number 2's crazy right? Could be done though...Any ideas on it would be greatly appreciated before I actually turn in the phone. Thanks again