Whenever I press the Volume Down Button on my SP3, it takes the volume straight down to 0 (i.e. the device becomes muted). For example, if the volume is currently at 55 and I press the volume down button once (for like half of a second), instead of the volume going down to 54 and stopping, it keeps sliding all the way down to 0. I don't think this was the behaviour of that button at first, but I think it began happening after some usage (and perhaps after installing quite a few updates). Is this normal? Does this happen to everyone? Is there a way to change this?