I have the latest revision 2.16 ghz white Macbook. The sound sometimes seems to cut in and out. When I try to turn the volume up or down, it seems to stutter and below the volume bars it has a circle with a line through it (like a no smoking symbol). It has 3 GB of RAM, so I don't that is an issue ( I also had the problem before I installed the RAM). Is this a problem in the Macbooks? Any Ideas?