There might be "JUST ENOUGH" corrosion in it to make it act this way. My Galaxy S2 Skyrocket also does this but mine only stops working occasionally. I dropped mine in a bowl of cereal (please don't ask) and have it's had some hard landings at work onto some big drills without a case on. Sometimes if I give my phone a smack on the back it'll work again normally. Not too hard, but it helps.