Macbook Sound cuts in and out

[Brandhaus]

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?

 

[Brandhaus]

Also, the weirdest thing, when I go to sound in system preferences, the volume slider seems to go gray and come back by itself, as if its shorting out or something.