Any time I adjust the way I'm sitting, or move my laptop a bit, I hear this small clicking noise inside. I'm almost 100% certain this noise is the SMS kicking in to protect the hard drive, but I wanted to be sure nothing else could be wrong with it. I bought it about a week ago. I've had a MB since 2008 and have never heard the SMS kick in (although, I knows its in there), which is the main reason why I'm asking. The screen also dims down for a split second when this happens.