I have been using my M for almost a month now...the one thing i cannot figure out is that i frequently get a notification....this happens often like every 20 minutes it seems....it sounds like a doorbell....the light doesnt come on...the screen doesnt light up....theres nothing in my notification bor or pane....its driving me nuts....does anyone have any ideas what this can be.....the sound sounds like a doorbell....best way i can descibe it