Sound on videos crackles PLEASE HELP

[asdfgbg]

Hey,

I noticed a strange crackling noise when I change the volume on streaming videos.
For example when I watch a YouTube video and I want to decrease the volume, I get almost always a strange crackling noise.
It's just when I stream a video.
The same video I bought on iTunes runs perfectly fine and I don't have that strange noise.
I already updated Flash but it didn't solve the problem.
I also tried HTML5 and there is the noise too.

Any thoughts what I should do ?

 

[Zeov]

for some reason mine stops either with a restart or if i shut down Safari...

 

[asdfgbg]

for some reason mine stops either with a restart or if i shut down Safari...

You have the same prob ?

 

[Zeov]

You have the same prob ?

not exactly, but when watching videos, i get this crackling sound every now and then, it's anoying as hell.