I'm having the exact same problems and am getting pretty frustrated. I don't have any warez, I've done a hard reset, I've tried it without a memory card and it still happens a couple times a week, most often when on a call, though sometimes once a month or so, the phone is idle and reboots itself. I also get the "Battery low" indicator when the battery if full, it restarts itself and then it is full again... (though it never really drained)... It seems to be totally sporadic to me.