My MacBook makes kind of a clicking sound sometimes, not very loud but audible. It does this every now and then, even when the computer is idle. Also, there is a grinding/clicking sound when things are loading (like when I start up my computer). I ran Disk Utility and it said everything checked out OK. I thought this clicking sound was troubling considering Macs are supposed to run silent, am I in trouble or is everything OK as Disk Utility said? Ideas?