Yesterday i was sitting at the pc and heard whatsapp notification and guess what...the vibration its not so hard as the phone was...its like a tiny bug...and feels like nothing...whats the problem?where its my strong vibration from ativ s..i'm using windows phone 8.1 beta...maybe its a bug?a hard reset wil remake the vibration? or wait 8.1 for oem drivers...i dont know..